Quarterly Journal of Experimental Psychology
ISSN: 0033-555X (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/pqje19
What can you do with your larynx? a rejoinder to clarkson and deutsch A. B. Rostron To cite this article: A. B. Rostron (1978) What can you do with your larynx? a rejoinder to clarkson and deutsch, Quarterly Journal of Experimental Psychology, 30:1, 171-174, DOI: 10.1080/14640747808400666 To link to this article: http://dx.doi.org/10.1080/14640747808400666
Published online: 21 Jun 2007.
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Date: 05 November 2015, At: 17:18
Quarterly Journal of Experimental Psychology (1978)30, 171-174
Downloaded by [University of Nebraska, Lincoln] at 17:18 05 November 2015
WHAT CAN YOUDO WITH YOUR LARYNX? A REJOINDER TO CLARKSON AND DEUTSCH A. B. ROSTRON Department of Psychology, The University, Hull, U.K. Deutsch and Clarkson suggest that fast control corrections, at the rate of about IO/S, take place when a human subject is required to sing a steady note (Deutsch and Clarkson, 1959; Clarkson and Deutsch, 1966). Should such rapid, accurate corrections take place, this would have a number of practical and theoretical implications. However, despite their arguments, the data presented by Deutsch and Clarkson do not appear to distinguish clearly between a cycle by cycle theory and an envelope theory. Clarkson and Deutsch (1977) assert that I was unable to replicate their 1959 findings of the effects of delayed auditory feedback (DAF) on vibrato amplitude and frequency. Their demonstration is, in fact, readily reproducible, provided that comparable time delays of the auditory feedback are used. Their data show an increasing effect of the delay, with a maximum effect using a delay of 500600 ms. However, delays of this magnitude seem inappropriate to distinguish between the cycle by cycle and envelope theories of control. If the cycle by cycle theory is applicable, then it is working at the rate of about 10 control corrections per second and it would therefore seem that progressively increasing delays of up to about IOO ms should produce a systematic decrease in control. Feedback delays in the range of 0-100 ms provide a more appropriate test of the cycle by cycle theory than delays in the range from 100-550 ms since it is unlikely that a cycle by cycle system could be delayed by this amount without becoming totally unstable. Even if a cycle by cycle control system could be persuaded to work with such long delays then the vibrato amplitude would be much higher and the vibrato period much longer than that found by Clarkson and Deutsch (1959). However, to test the cycle by cycle theory with such long delays is not fair since it can always be argued that failure to reach the vibrato amplitude and period values predicted might be due to a change in the mode of control. Therefore the main difference in experimental conditions in the original Deutsch and Clarkson (1959) DAF experiment and the experiment reported by Rostron (1976) is in the feedback delays used, and consequently the results are not directly comparable. I would argue that both Deutsch and Clarkson (1959) and Rostron (1976) support an envelope theory of pitch control since both short and long delays do not produce the extent of decrease in control predicted by a
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cycle by cycle theory. Precise quantitative estimates of the changes in degree of control as the delay is introduced can be made for the cycle by cycle theory; for details of this procedure see Rostron (1970). In no case was there any evidence of agreement between these predictions and the measured changes in control in any of the subjects used. The predictions work on an individual basis and even if only one subject had come up with good agreement with theory this would have indicated that some subjects at least might control pitch on a cycle by cycle basis. The absence of such supportive evidence suggests that the cycle by cycle model is inappropriate in this situation. Although the preceding argument elaborates to a certain extent the rationale for distinguishing between envelope and cycle by cycle control it is still possible, as Clarkson and Deutsch (1977) point out, that the way in which the data were obtained does not provide a fair test of the theories. I would argue that the procedures employed did constitute a valid test. First it was possible with the computer delayed feedback to produce effects similar to those found by Deutsch and Clarkson (1959)with similar delays and there was little sign that the effects of DAF had been overcome by the end of an experimental session. (In a number of experiments Rostron (1970) found no sign of large and systematic extended practice effects.) Second, if there were any essential differences in the techniques of the present author and Deutsch and Clarkson (1959) in measuring vibrato amplitude and frequency then this should show up when comparing these no measures on the two conditions, no earphones and no delay, and earphones delay. In fact the differences found between these two conditions and reported by Deutsch and Clarkson (1959) are very comparable to those described by Rostron ( I 970). It is also probable that the instrumentation did produce an accurate record of the frequency output of the subjects, since more recent recordings with a different pitch extractor (Rostron and Welbourn, 1976), are qualitatively very similar to those produced on the original apparatus. In fact, vibrato records of subjects attempting to sing a constant frequency are not particularly regular and do exhibit relatively slow drifts as the note is produced, although it is true that some subjects do produce traces which are relatively regular and have no overall drift. The author’s published records are rather longer than those of Deutsch and Clarkson (1959) and would therefore tend to show up any overall drifts more readily. Therefore picking out sections which look stable and show the subject oscillating clearly at about the right rate would seem to bias the results in favour of the cycle by cycle theory. Furthermore if the cycle by cycle theory is being tested thoroughly, then measures not only of vibrato amplitude and frequency must be made, but drift rate values must also be recorded. It is only possible to do this if decisions are made about what are, and what are not, control corrections. Admittedly the experimenter may well be wrong in identifying specific control corrections, but on a cycle by cycle theory most of the corrections should be fairly obvious. Another method of overcoming this essential subjectivity is to reanalyse a given trace a number of times with the several different possibilities and see whether any of these traces fit the predictions required by the cycle by cycle model. On samples where this was tried, there were again no cases in
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Downloaded by [University of Nebraska, Lincoln] at 17:18 05 November 2015
A REJOINDER TO CLARKSON AND DEUTSCH
‘73
which feedback delays estimated by using the recorded vibrato periods and amplitudes with the theoretical model, matched the real delay value actually presented. This must surely be convincing evidence against a cycle by cycle theory of pitch control. I t is quite possible that cycle by cycle control might occur concurrently with slower control corrections, and it would therefore seem an appropriate procedure to remove any slow frequency drifts which might be control corrections to enable the faster frequency changes to be examined in more detail. T o get support for cycle by cycle control, the strategy of testing for it where it is most likely to be working would seem to be bending over backwards to obtain evidence for it. Despite this, no evidence to support the cycle by cycle theory was found. As far as power spectrum analysis is concerned, it is certainly inappropriate here since it only produces an indication of the relative powers of the various frequencies present. This information is not sufficient to enable a distinction to be made between cycle by cycle and envelope control. The fact that singers can control vibrato should not be regarded as evidence of a cycle by cycle theory for a number of reasons. First, the vibrato used for artistic purposes is somewhat larger, and also more regular, with fewer slow frequency drifts than that produced by subjects attempting to produce a steady frequency. (I also have some objective, but unpublished evidence for this from vibrato records of singers and non-singers and also from records of singers using their normal singing voice and singers attempting to sing a note with as little vibrato as possible.) Secondly control of vibrato rate and frequency might well be achieved by means other than cycle by cycle control. For example vibrato may be some sort of oscillatory phenomenon, and successive frequency changes may not be control corrections either voluntary or involuntary. I t should also be stressed that the envelope theory does not state that vibrato is “physiological wobble”, but merely that some of the frequency changes making up the vibrato may be due to physiological wobble. (Other changes may be due to still other factors such as intensity changes affecting the frequency output.) Again it should be mentioned that the envelope theory does not claim that control corrections are made at a typical interval of 1.5 s, but at some unspecified and probably variable interval of less than 1.5 s. I t is also worth spelling out one implication of the envelope theory that is not immediately obvious and this is that individual control corrections may not be readily identifiable from frequency records however good they are, because they may be superimposed at irregular intervals on physiological noise. This possibility can be illustrated by considering the output of the violinist who might control the produced frequency by turning a tuning peg whilst simultaneously altering the frequency by varying the position of the finger on the bowed string. I n conclusion I would therefore argue that the sets of data presented by Deutsch and Clarkson (1959) and Clarkson and Deutsch (1966) are consistent with both envelope and cycle by cycle theories of pitch control and that the data and theoretical analysis presented by Rostron (1970, 1976) enable a distinction to be made between the two theories, enabling the cycle by cycle theory to be conclusively rejected. I t is still plausible that some form of cycle by cycle control
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occurs when a note is initiated, since Rostron and Sewell (1978) have demonstrated that whenever an attempt is made to match a steady frequency the output does not in general stabilize until about 500 ms after the start of the note, and that there are several rather large frequency oscillations before the final stabilization. The rate of stabilization is slowed by an auditory white noise background, so it is likely that the stabilization process is dependent on auditory feedback.
Downloaded by [University of Nebraska, Lincoln] at 17:18 05 November 2015
References CLARKSON, J. K. and DEUTSCH, J. A. (1966). Effect of threshold reduction on the vibrato. Journal of Experimental Psychology, 71,706-10. CLARKSON, J. K. and DEUTSCH, J. A. (1978). Pitch control in the human voice: a reply to A. B. Rostron. Quarterly Journal of Experimental Psychology, 30, 167-9. DEUTSCH, J. A. and CLARKSON, J. K. (1959). Nature of the vibrato and the control loop in singing. Nature, 183,167-8. ROSTRON, A. B. (1970). Some experiments in pitch perception (Unpublished doctoral dissertation, University of Reading). ROSTRON, A. B. (1976). Pitch control in the human voice. Quarterly Journal of Experimental Psychology, 28, 305-10. ROSTRON, A. B. and SEWELL, D. F. (1978). Manuscript submitted for publication. ROSTRON, A. B. and WELBOURN, C. P. (1976). A computer assisted system for the extraction and visual display of pitch. Behaviour Research Methods and Instrumentation, 8 , 456-9. Received 10M a y 1977
ISSN: 0033-555X (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/pqje19
What can you do with your larynx? a rejoinder to clarkson and deutsch A. B. Rostron To cite this article: A. B. Rostron (1978) What can you do with your larynx? a rejoinder to clarkson and deutsch, Quarterly Journal of Experimental Psychology, 30:1, 171-174, DOI: 10.1080/14640747808400666 To link to this article: http://dx.doi.org/10.1080/14640747808400666
Published online: 21 Jun 2007.
Submit your article to this journal
Article views: 3
View related articles
Citing articles: 2 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=pqje19 Download by: [University of Nebraska, Lincoln]
Date: 05 November 2015, At: 17:18
Quarterly Journal of Experimental Psychology (1978)30, 171-174
Downloaded by [University of Nebraska, Lincoln] at 17:18 05 November 2015
WHAT CAN YOUDO WITH YOUR LARYNX? A REJOINDER TO CLARKSON AND DEUTSCH A. B. ROSTRON Department of Psychology, The University, Hull, U.K. Deutsch and Clarkson suggest that fast control corrections, at the rate of about IO/S, take place when a human subject is required to sing a steady note (Deutsch and Clarkson, 1959; Clarkson and Deutsch, 1966). Should such rapid, accurate corrections take place, this would have a number of practical and theoretical implications. However, despite their arguments, the data presented by Deutsch and Clarkson do not appear to distinguish clearly between a cycle by cycle theory and an envelope theory. Clarkson and Deutsch (1977) assert that I was unable to replicate their 1959 findings of the effects of delayed auditory feedback (DAF) on vibrato amplitude and frequency. Their demonstration is, in fact, readily reproducible, provided that comparable time delays of the auditory feedback are used. Their data show an increasing effect of the delay, with a maximum effect using a delay of 500600 ms. However, delays of this magnitude seem inappropriate to distinguish between the cycle by cycle and envelope theories of control. If the cycle by cycle theory is applicable, then it is working at the rate of about 10 control corrections per second and it would therefore seem that progressively increasing delays of up to about IOO ms should produce a systematic decrease in control. Feedback delays in the range of 0-100 ms provide a more appropriate test of the cycle by cycle theory than delays in the range from 100-550 ms since it is unlikely that a cycle by cycle system could be delayed by this amount without becoming totally unstable. Even if a cycle by cycle control system could be persuaded to work with such long delays then the vibrato amplitude would be much higher and the vibrato period much longer than that found by Clarkson and Deutsch (1959). However, to test the cycle by cycle theory with such long delays is not fair since it can always be argued that failure to reach the vibrato amplitude and period values predicted might be due to a change in the mode of control. Therefore the main difference in experimental conditions in the original Deutsch and Clarkson (1959) DAF experiment and the experiment reported by Rostron (1976) is in the feedback delays used, and consequently the results are not directly comparable. I would argue that both Deutsch and Clarkson (1959) and Rostron (1976) support an envelope theory of pitch control since both short and long delays do not produce the extent of decrease in control predicted by a
'7'
Downloaded by [University of Nebraska, Lincoln] at 17:18 05 November 2015
‘72
A. B. ROSTRON
cycle by cycle theory. Precise quantitative estimates of the changes in degree of control as the delay is introduced can be made for the cycle by cycle theory; for details of this procedure see Rostron (1970). In no case was there any evidence of agreement between these predictions and the measured changes in control in any of the subjects used. The predictions work on an individual basis and even if only one subject had come up with good agreement with theory this would have indicated that some subjects at least might control pitch on a cycle by cycle basis. The absence of such supportive evidence suggests that the cycle by cycle model is inappropriate in this situation. Although the preceding argument elaborates to a certain extent the rationale for distinguishing between envelope and cycle by cycle control it is still possible, as Clarkson and Deutsch (1977) point out, that the way in which the data were obtained does not provide a fair test of the theories. I would argue that the procedures employed did constitute a valid test. First it was possible with the computer delayed feedback to produce effects similar to those found by Deutsch and Clarkson (1959)with similar delays and there was little sign that the effects of DAF had been overcome by the end of an experimental session. (In a number of experiments Rostron (1970) found no sign of large and systematic extended practice effects.) Second, if there were any essential differences in the techniques of the present author and Deutsch and Clarkson (1959) in measuring vibrato amplitude and frequency then this should show up when comparing these no measures on the two conditions, no earphones and no delay, and earphones delay. In fact the differences found between these two conditions and reported by Deutsch and Clarkson (1959) are very comparable to those described by Rostron ( I 970). It is also probable that the instrumentation did produce an accurate record of the frequency output of the subjects, since more recent recordings with a different pitch extractor (Rostron and Welbourn, 1976), are qualitatively very similar to those produced on the original apparatus. In fact, vibrato records of subjects attempting to sing a constant frequency are not particularly regular and do exhibit relatively slow drifts as the note is produced, although it is true that some subjects do produce traces which are relatively regular and have no overall drift. The author’s published records are rather longer than those of Deutsch and Clarkson (1959) and would therefore tend to show up any overall drifts more readily. Therefore picking out sections which look stable and show the subject oscillating clearly at about the right rate would seem to bias the results in favour of the cycle by cycle theory. Furthermore if the cycle by cycle theory is being tested thoroughly, then measures not only of vibrato amplitude and frequency must be made, but drift rate values must also be recorded. It is only possible to do this if decisions are made about what are, and what are not, control corrections. Admittedly the experimenter may well be wrong in identifying specific control corrections, but on a cycle by cycle theory most of the corrections should be fairly obvious. Another method of overcoming this essential subjectivity is to reanalyse a given trace a number of times with the several different possibilities and see whether any of these traces fit the predictions required by the cycle by cycle model. On samples where this was tried, there were again no cases in
+
Downloaded by [University of Nebraska, Lincoln] at 17:18 05 November 2015
A REJOINDER TO CLARKSON AND DEUTSCH
‘73
which feedback delays estimated by using the recorded vibrato periods and amplitudes with the theoretical model, matched the real delay value actually presented. This must surely be convincing evidence against a cycle by cycle theory of pitch control. I t is quite possible that cycle by cycle control might occur concurrently with slower control corrections, and it would therefore seem an appropriate procedure to remove any slow frequency drifts which might be control corrections to enable the faster frequency changes to be examined in more detail. T o get support for cycle by cycle control, the strategy of testing for it where it is most likely to be working would seem to be bending over backwards to obtain evidence for it. Despite this, no evidence to support the cycle by cycle theory was found. As far as power spectrum analysis is concerned, it is certainly inappropriate here since it only produces an indication of the relative powers of the various frequencies present. This information is not sufficient to enable a distinction to be made between cycle by cycle and envelope control. The fact that singers can control vibrato should not be regarded as evidence of a cycle by cycle theory for a number of reasons. First, the vibrato used for artistic purposes is somewhat larger, and also more regular, with fewer slow frequency drifts than that produced by subjects attempting to produce a steady frequency. (I also have some objective, but unpublished evidence for this from vibrato records of singers and non-singers and also from records of singers using their normal singing voice and singers attempting to sing a note with as little vibrato as possible.) Secondly control of vibrato rate and frequency might well be achieved by means other than cycle by cycle control. For example vibrato may be some sort of oscillatory phenomenon, and successive frequency changes may not be control corrections either voluntary or involuntary. I t should also be stressed that the envelope theory does not state that vibrato is “physiological wobble”, but merely that some of the frequency changes making up the vibrato may be due to physiological wobble. (Other changes may be due to still other factors such as intensity changes affecting the frequency output.) Again it should be mentioned that the envelope theory does not claim that control corrections are made at a typical interval of 1.5 s, but at some unspecified and probably variable interval of less than 1.5 s. I t is also worth spelling out one implication of the envelope theory that is not immediately obvious and this is that individual control corrections may not be readily identifiable from frequency records however good they are, because they may be superimposed at irregular intervals on physiological noise. This possibility can be illustrated by considering the output of the violinist who might control the produced frequency by turning a tuning peg whilst simultaneously altering the frequency by varying the position of the finger on the bowed string. I n conclusion I would therefore argue that the sets of data presented by Deutsch and Clarkson (1959) and Clarkson and Deutsch (1966) are consistent with both envelope and cycle by cycle theories of pitch control and that the data and theoretical analysis presented by Rostron (1970, 1976) enable a distinction to be made between the two theories, enabling the cycle by cycle theory to be conclusively rejected. I t is still plausible that some form of cycle by cycle control
'74
A. B. BOSTRON
occurs when a note is initiated, since Rostron and Sewell (1978) have demonstrated that whenever an attempt is made to match a steady frequency the output does not in general stabilize until about 500 ms after the start of the note, and that there are several rather large frequency oscillations before the final stabilization. The rate of stabilization is slowed by an auditory white noise background, so it is likely that the stabilization process is dependent on auditory feedback.
Downloaded by [University of Nebraska, Lincoln] at 17:18 05 November 2015
References CLARKSON, J. K. and DEUTSCH, J. A. (1966). Effect of threshold reduction on the vibrato. Journal of Experimental Psychology, 71,706-10. CLARKSON, J. K. and DEUTSCH, J. A. (1978). Pitch control in the human voice: a reply to A. B. Rostron. Quarterly Journal of Experimental Psychology, 30, 167-9. DEUTSCH, J. A. and CLARKSON, J. K. (1959). Nature of the vibrato and the control loop in singing. Nature, 183,167-8. ROSTRON, A. B. (1970). Some experiments in pitch perception (Unpublished doctoral dissertation, University of Reading). ROSTRON, A. B. (1976). Pitch control in the human voice. Quarterly Journal of Experimental Psychology, 28, 305-10. ROSTRON, A. B. and SEWELL, D. F. (1978). Manuscript submitted for publication. ROSTRON, A. B. and WELBOURN, C. P. (1976). A computer assisted system for the extraction and visual display of pitch. Behaviour Research Methods and Instrumentation, 8 , 456-9. Received 10M a y 1977
