Stimulus sequence and the exponent of the power function for loudness.

Area of Science:

• Psychoacoustics
• Auditory perception
• Psychophysics

Background:

• Understanding loudness perception is crucial for fields like audio engineering and audiology.
• Previous research has established a general relationship between sound pressure and perceived loudness.

Purpose of the Study:

• To investigate how the order of sound stimuli presentation affects loudness estimation.
• To determine the exponent of the power function relating loudness to sound pressure under different presentation orders.
• To explore assimilation effects and momentary exponents in loudness perception.

Main Methods:

• Two experiments involving 15 and 13 subjects, respectively.
• Magnitude estimation of loudness for a 1000-Hz tone across 12 sound pressure levels (38-104 dB).
• Systematic ascending-descending and balanced-irregular stimulus presentation orders were used.

Main Results:

• Loudness was found to be a power function of sound pressure with exponents of 0.60 (systematic) and 0.29 (irregular).
• Assimilation effects were observed with larger step-sizes (12-18 dB) and also with small step-sizes (6 dB) in the irregular order.
• Momentary exponents were influenced by successive stimulus sound pressures, step direction, and presentation order, with effects more pronounced in the irregular order.

Conclusions:

• The order of stimulus presentation significantly impacts the exponent of the loudness-sound pressure function.
• A relative judgment model, incorporating minimum, maximum, and previous stimulus sound pressures, is proposed to explain magnitude estimation.
• Auditory perception of loudness is context-dependent, influenced by sequential stimulus characteristics.