Method of measuring frequency selectivity, and method and apparatus for estimating auditory filter shape by a frequency selectivity measurement method

A method of measuring frequency selectivity comprising the steps of:

• adding noises having predetermined notch widths generated from white noise set at a threshold masking level to a detection sound whose frequency and sound pressure are set at predetermined values to produce a series of different inspection sounds which are different from each other only in the value of the predetermined notch width of the noise added thereto;
• transmitting the series of inspection sounds to a subject one at a time;
• judging whether or not the subject can perceive the detection sound from each of the inspection sounds;
• and
• obtaining a threshold notch width of the subject.

A method of estimating a shape of an auditory filter by finding a coefficient p of a roex (p, r) filter used as a model of the shape of the auditory filter, comprising the steps of:

• determining a threshold masking level Nx based on a tone S which adds a given value x to a threshold of hearing T of a subject in frequency f;
• generating a tone S′ which deducts a given value a from the tone S;
• generating a masker M of notch width g and level Nx including the frequency f in a notch;
• transmitting a detection sound which superposes the masker M on the tone S′ to a subject;
• measuring a minimum notch width gx−a of the subject by changing the notch width g;
• calculating a coefficient p from the minimum notch width gx−a and a given value a;
• and
• estimating the shape of the auditory filter from the coefficient p and the given value x corresponding to a coefficient r.

An apparatus for estimating a shape of an auditory filter by finding a coefficient p of a roex (p, r) filter used as a model of the shape of the auditory filter comprising:

• a tone generation element for generating a tone of a predetermined frequency;
• a tone level setting element for amplifying or attenuating the tone generated from the tone generation element to a predetermined level;
• a noise generation element for generating noise without a notch;
• a noise level setting element for amplifying or attenuating the noise generated at the noise generation element to a predetermined level;
• a notch width setting element for providing a notch including frequency of the tone to the noise;
• a notched noise superposing element for superposing the notched noise output from the notch width setting element on the tone output from the tone level setting element, and outputting an inspection sound based thereon;
• an inspection sound transmission element for transmitting the inspection sound output from the notched noise superposition element to a subject;
• and
• an auditory filter calculation and indication element for calculating a coefficient p of a roex (p, r) filter based on the notch width at which the subject can perceive the inspection sound and indicating the filter shape from the coefficients p and r obtained.

Apparatus for estimating a shape of an auditory filter by finding a coefficient p of a roex (p, r) filter used as a model of the shape of the auditory filter, comprising:

• means for determining a threshold masking level Nx based on a tone S which adds a given value x to a threshold of hearing T of a subject in frequency f;
• means for generating a tone S′ which deducts a given value a from the tone S;
• means for generating a masker M of notch width g and level Nx including the frequency f in a notch;
• means for transmitting a detection sound which superposes the masker M on the tone S′ to a subject;
• means for measuring a minimum notch width gx−a of the subject by changing the notch width g;
• means for calculating a coefficient p from the minimum notch width gx−a and a given value a;
• and
• means for estimating the shape of the auditory filter from the coefficient p and the given value x corresponding to a coefficient r.