David M. Green

Frequency discrimination as a function of frequency and sensation level

Frequency discrimination was measured for frequencies from 200 to 8000 Hz and for sensation levels from 5 to 80 dB using pulsed sinusoids as stimuli in an adaptive two‐interval force‐choice psychophysical procedure. An analysis of variance indicated significant effects of frequency and sensation level, and of the interaction between frequency and sensation level. The effect of sensation level is greatest at low frequencies and decreases at high frequenices, being quite small at 8000 Hz. The data are used to evaluate the predictions of current theoretical models.

Intensity discrimination as a function of frequency and sensation level

Intensity discrimination was measured for pulsed sinusoids of various frequencies (200–8000 Hz) and sensation levels (5–80 dB). The data for all frequencies were fitted by a single function, ΔI/I=0.463 (I/I0)−0.072, where I0 is intensity at threshold, I is the intensity of the tone, and ΔI is the increment needed to obtain 71% correct in a two‐interval forced‐choice adaptive procedure. The form of this function is in good agreement with data reported in comparable studies but differs markedly from the data reported by Riesz [Phys. Rev. 31, 867–875 (1928)]. An analysis of the actual values of ΔI/I reported in the other studies indicates a range larger than would be predicted on the basis of individual differences among observers in this study. The data are also discussed differences among observers in this study. The data are also discussed in terms of the predictions of current theoretical models.

Auditory Detection of a Noise Signal

Measurements of the detectability of a noise signal in noise are reported in this paper. Parameters of the noise signal such as the band width, duration, and center frequency are investigated. The results are compared with an optimum‐detection model. For some constant detectability the equation generated by the model and one constant, an attenuation factor, closely fit the experimental data over the major range of the experimental parameters. The major area of discrepancy between model and data is the shape of the psycho‐physical function. Implications of the data for the critical‐band mechanism are also discussed.

Psychoacoustics and Detection Theory

This paper presents a fairly complete review of detection theory as it is applied to certain psychoacoustic data. Detection theory is treated as a combination of two theoretical structures: decision theory and the concept of ideal observer. The paper discusses how statistical decision theory has been used to analyze the auditory threshold process. By treating the threshold process as an instance of hypothesis testing, two determinants of the process are recognized: (1) the detectability of the signal and (2) the criterion level of the observer. The theory provides a technic of analysis which allows one to obtain a quantitative estimate of both factors. The measure of signal detectability appears to be independent of the psychophysical procedure when the physical parameters of signal and noise are held constant. The concept of ideal observer is reviewed with special emphasis on the assumptions of the derivation. The usefulness of this concept is illustrated by considering the shape of the psychophysical fu...

A maximum-likelihood method for estimating thresholds in a yes-no task.

A maximum-likelihood procedure for estimating threshold values in a yes-no task is presented. In computer simulations of this procedure, it is demonstrated that the variability of the threshold estimates is little affected by the density of the hypotheses tested for a fixed range, or by serious misestimates of the slope of the psychometric functions. The threshold value is also largely independent of the starting value of the signal. The standard deviation of the threshold estimates appears to decrease with the square root of the number of trials, with a 2- to 3-dB standard deviation possible if only 12 trials are used in the threshold estimates. Data are presented using human listeners tested on 5 days. Two threshold estimates, based on 12 trials, were made at each of the six audiometric frequencies on each day. The mean data appear sensible, and the standard deviation of the measured thresholds is about 3 dB. Using this procedure, it takes less than 3 min to measure the audiogram for a single ear.

Sequential effects in judgments of loudness.

A multiple regression analysis of sequential effects in magnitude estimation and absolute identification is presented as an alternative to the approach used by Lockhead and his students. The new analysis indicates that sequential effects do not extend over more than one trial. This is in agreement with the response ratio hypothesis. A more detailed multiple regression analysis of these sequential effects indicates that the magnitude of the correlation between successive responses is heavily dependent on the decibel difference between successive signals. This is not in agreement with the response ratio hypothesis, and the hypothesis is reformulated to take account of this finding. This modification of the model is tested by comparing distributions of normalized responses to theoretical distributions suggested by the model and to a possible alternative distribution.

The bow and sequential effects in absolute identification

The bow and sequential effects in absolute identification are investigated in this paper by following two strategies: (1) Experiments are performed in which sequential dependencies in signal presentations are manipulated, and 12) analyses are conducted (some of which are largely free of model-specific assumptions) which bear directly on the question of the origin of the sequential effects. The main result of the study is that absolute identification performance is greatly improved in a design in which each signal lies close to the preceding signal presented, even though the entire range of signals used is the same as in a random presentation design. This finding is consistent with the attention-band model of Luce, Green, and Weber (1976) and rejects hypotheses that suggest that the variability in the signal representation in absolute identification is a function solely of the range of signals being used. However, nonparametric analyses of sequential response errors show that a plausible assumption concerning the trial by-trial movement of the attention band provides an incomplete explanation of Seluential effects in absolute identification. These results are far better explained in terms of systematic shifts of category boundaries in a Thurstonian model, as suggested by Purks, Callahan, Braida, and Durlach (1980). Experiments are also performed which suggest that memory decay is not the major factor accounting for the bow effect in absolute identification.

Variability and sequential effects in magnitude production and estimation of auditory intensity

Magnitude production and estimation data from the same subjects are analyzed in three ways. The coefficient of variation of the ratio of successive responses Inumbers in estimation, SPL in production) are compared; both exhibit, as a function of stimulus difference, the V-shaped pattern previously found in estimation data. A multiple regression of responses on the stimulus and on these events of the previous trial exhibit similar patterns, although the effects of the previous trial in production are somewhat less. The correlation between successive responses, averaged over constant stimulus differences, are very large for small differences and about zero for large ones. These somewhat surprisng results for production are examined from the point of view of an intensity attention band hypothesis.

Profile analysis : auditory intensity discrimination

Early experiments in profile analysis Intensity discrimination Discrimination of a change in intensity level for sinusoidal signals Some properties of profile analysis Frequency and relative level effects in profile analysis Training and dynamic effects Two theories of profile analysis.

Signal Detection as a Function of Signal Intensity and Duration

The object of this study was to determine how signal amplitude and duration effect the detectability of a pure tone partially masked by random noise. If signal duration and amplitude are considered two dimensions in a space, the study attempted to determine the surface of detectability in this space. To accomplish this task three experiments were conducted with the same observers in each experiment. In the first experiment signal duration was held constant while amplitude was varied. In the second experiment signal energy was held constant while various pairs of values of signal duration and amplitude were tested. Finally, signal amplitude was held constant while signal duration was varied. A three parameter equation was determined which provided a reasonable fit to this surface of detectability in the plane of signal amplitude and duration. The equations are consistent with the data of previous research in this area. Finally, a comparison of the results and the predictions generated by a simple filter model is discussed.