486F. MISKOLCZY-FODOR the same principle. This observation proves the rather general validity of the concept concerning the direct correlation between loudness and time threshold. •,a 2. The regular relationship between tone duration and loudness will be altered if the energy distribution of the pure tone noticeably changes along the frequency axis. This is due to transients associated with shortening of the tonal pulse. Under these conditions, the loudness response is affected by the increased energy dissipation over side bands, as well as the decreased signal duration.3. The time threshold depends, therefore, not only upon the loudness of a given suprathreshold level, but also upon changes of sound energy distribution along the frequency bands. Threshold changes affected by the altered energy distribution become apparent around the threshold of click pitch in behavioral experiments. We feel that this limit is dependent more upon behavioral responses to the side bands than upon the physical course of energy spreading. Subjective tran-sients may play a decisive role in the fairly sudden change of the subjective response around this limit. If the measured time threshold becomes shorter than click pitch, it has less bearing on the loudness of the original pure tone;rather, the time threshold becomes related to the loudness of the new sound, into which the pure tone is transformed by the transient modulation.4. It is not definite whether the duration limits of the described ranges are rather distinct, or whether they represent more continuous transitions. TM It is also conjectural whether the described duration ranges of shortened tonal pulses bear any closer relationship to the subjective limits of pitch changes (i.e., tone pitch, click pitch, click). The previously determined relation between time-threshold and loudness is investigated in cases ofabnormal loudness response. The correlation between loudness and duration of short sound impulses, academic dissertation, Budapest (1955). a F. Miskolczy-Fodor, Acta Oto-Laryngol. 43, 573 (1953). for a given level above threshold (time-threshold) is directly related to its loudness. Thus, the timethreshold determination appears to offer a suitable technique for measuring loudness over a specific range of suprathreshold levels. In order to ascertain the validity and practicability of the duration-loudness relation, the behavior of timethreshold in cases of pathologic loudness response was investigated. Certain previously published details, of this problem have been partially confirmed by Jerger, 4 4 j. F. Jerger, J. Acoust. Soc. Am. 27, 121 (1955). Redistribution subject to ASA license or copyright; see http://acousticalsociety.org/content/terms. Download to IP: 138.26.31.3 On: Tue, 23 Dec 2014 01:23:22 LOUDNESS AND DURATION IN PATHOLOGIC EARS 487 Eisenberg, 5 Harris, Haines, and Myers, 6 and discussed by R6sler and Lundborg. 7 The extensive papers by Eisenberg 5 and Harris et al., • dealing with the basic and practical problems of time-threshold measurements, deserve spec...

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IRWIN POLLACKAs expected, the d8 index decreases as the size of the exposure set is increased. A low performance level was approached with even the most proficient group of listeners for an exposure set of six sound levels--a total set of twelve sound levels. DISCUSSIONOne of the questions often addressed to the results of identification studies is, "How many sounds can be identified by the listener?" Since the & index will vary with the size of the exposure set in the method of recognition memory, any statement about the equivalent number of identifiable tones must also include the & criterion required. If a 75% correct two-way symmetrical classification--equivalent to a d, of 1.32-is employed, as is often the case in psychophysical studies, we would conclude that the listeners can employ an exposure set of 2 to 3 sound levels, or a combined set of about 5 sound levels. This result matches closely with studies which required the listener to assign arbitrary designations to the sound levels. 5 Finally, it may be noted that the method of recognition memory, itself, has not imposed the final ceiling upon performance. Nearly perfect discrimination has been obtained with this method, for example, for exposure sets of several hundred sentences. 6In normal ears, threshold intensity as a function of the duration of a tonal pulse is determined. Identical results are obtained by a reciprocal determination. The reciprocal determination is made by fixing the intensity level at specified points above reference threshold to measure the time threshold. The durationintensity relationship reveals a marked dependency upon frequency; the differences observed are equivalent to the alteration of loudness function for the various test frequencies. A new measure of loudness increment degree, as well as conversion of decibel values into phon and sone values, indicates a close relationship between time threshold and loudness sensation. Therefore, the relationship between pulse duration and loudness level presents no artifacts reflecting frequency-dependent changes. The time threshold (T msec), as a fraction of pulse duration re the "adjusting time" of the auditory mechanism (150/T), seems to indicate the loudness of related levels above threshold in sones. General conclusions deriving from these relationships and some limitations of their applicability are discussed in detail; these are confirmed by a comparison between monaural and binaural time-threshold measurements.

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