Biomedical subjects

G B Henning

Publications and source records attributed to G B Henning.

At least 55 records · Page 3Linked to original sources

PubMed1981

The effect of noise on time-intensity trading in lateralization.

A two-interval forced-choice lateralization task was used to determine interaural delays and interaural amplitude ratios which, when opposed in quiet, led to chance lateralization; the opposed cues formed time-intensity trades. Three types of signal were used: (1) 20-microseconds clicks; (2) 250-ms bursts of a 305 Hz tone; and (3) 250-ms bursts of 3965 Hz carrier amplitude modulated to a depth of 100% at a modulation rate of 305 Hz. The addition of various levels of broad-band white noise did not influence the relative effectiveness of the two lateralization cues with pure tone signals; however, the addition of noise to clicks and to AM waveforms led to lateralization judgements in which the cue based on interaural delay appeared to be less effective than in quiet.

Acoustic Stimulation↗

PubMed1981

Binaural masking level differences with a variety of waveforms.

Binaural masking level differences (BMLDs) were measured in a standard two-interval forced-choice detection task. The signals were (a) 250-ms bursts of pure tones, (b) amplitude-modulated waveforms with either high- or low-frequency carriers, and (c) 20-microseconds clicks. The pure tones and clicks were presented either eith zero phase difference between the ears or with an 180 degrees phase difference between the ears: the AM tones were presented in several different interaural phase conditions, only some of which lead to changes in the apparent location of the signal source. The noise against which all the signals were detected was white, broad-band, and identical at the ears. BMLDs were invariably small with high-frequency signals and with clicks. Although the magnitude of the BMLD obtained with low-frequency signals appeared to be related to the Observers' ability to lateralize the signal, there is a simpler explanation based on the assumption that detection of low-frequency AM signals is determined by independent detection of its components.

Acoustic Stimulation↗

PubMed1981

The effect of carrier and modulation frequency on lateralization based on interaural phase and interaural group delay.

The sensitivity of Observers to interaural delay in either the envelope or the carrier of an amplitude-modulated sinusoid was measured in a two-interval forced-choice task as a function of the frequency of the modulation and the frequency of the carrier. The two types of delay were set in opposition with the carrier leading in one ear but the modulation leading in the other. Lateralization appeared to be based on carrier (phase) delay when carrier frequency was below 1500 Hz, whatever the modulation frequency. For carrier frequency greater than 1500 Hz, lateralization performance was dependent both on carrier and on modulation frequency and was based on modulation (group) delay.

Acoustic Stimulation↗

PubMed1981

Effects of different hypothetical detection mechanisms on the shape of spatial-frequency filters inferred from masking experiments: I. Noise masks.

The detectability of a sinusoidal grating was measured in a standard two-interval forced-choice experiment against backgrounds of noise gratings of the same orientation as the signal. The noise gratings were either spatially high-pass or low-pass filtered and were either unchanged in each observation interval (static) or flickering at a rate that depended on their cutoff frequency (dynamic). Spatial-frequency-selective mechanisms are inferred from the data and their characteristics shown to depend on assumptions concerning the detection process thought to follow the spatial-frequency-selective device.

Humans↗

PubMed1980

Some observations on the lateralization of complex waveforms.

Consistent lateralization judgement can be obtained with interaural delays in the envelope but not in the carrier of high-frequency sinusoidal signals that are amplitude modulated. At low frequencies the situation is reversed and delays in the carrier, but not the envelope, can be detected. Delays in quasi-frequency-modulated or frequency-modulated waveforms allow lateralization by some observers but require much larger delays for performance as good as that obtained with amplitude-modulated signals. The implications of some of these observations for models of the envelope extraction process are discussed.

Auditory Perception↗

PubMed1977