# US 8,571,224 B2 · System for estimating sound pressure levels at the tympanic membrane using pressure-minima based distance

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 8,571,224 B2
- Document ID: US8571224B2
- Status: Granted
- Kind: B2
- Application number: 12/537,908
- Filed: 2009-08-07
- Published: 2010-10-14
- Granted: 2013-10-29
- Earliest claimed: 2008-08-08
- Assignees: Starkey Laboratories, Inc.
- Applicants: Karrie LaRae Recker; Tao Zhang; Wei Li Lin
- Inventors: Karrie LaRae Recker; Tao Zhang; Wei Li Lin
- Web page: https://patentgrep.com/patent/US8571224B2

## CPC

- A61B 5/121: {evaluating hearing capacity}
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

In various embodiments, a system is used to provide an apparatus configured to measure sound in an ear canal of a wearer's ear at a distance from a tympanic membrane of the ear. The sound is measured and received by the apparatus to produce a signal. A frequency analysis is performed on the signal to determine output as a function of the frequency and to determine the frequency of the minima (null). Further, a distance equal to a quarter wavelength of the null frequency is calculated. A correction factor associated with the quarter wavelength is retrieved and applied to the output to generate a corrected output. An estimated sound pressure level at the tympanic membrane from the corrected output is produced.

## Claims

### Claim 1

A method, comprising:
providing an apparatus configured to measure sound in an ear canal of a wearer's ear at a distance from a tympanic membrane of the ear;
measuring sound at a single location in the ear received by the apparatus to produce a signal;
performing frequency analysis on the signal to determine output as a function of the frequency;
determining a null frequency of a minima of the output according to the measurement at the single location;
calculating a distance equal to a quarter wavelength of the null frequency;
retrieving a previously generated correction factor associated with the quarter wavelength;
applying the correction factor to the output to generate a corrected output; and
producing an estimated sound pressure level at the tympanic membrane from the corrected output.

### Claim 2 (depends on 1)

The method of claim 1, wherein performing the frequency analysis includes performing a fast Fourier transform (FFT) on the signal.

### Claim 3 (depends on 1)

The method of claim 1, wherein the correction factor is a function of width of the minima.

### Claim 4 (depends on 1)

The method of claim 1, wherein the correction factor is a function of depth of the minima.

### Claim 5 (depends on 1)

The method of claim 1, further comprising generating a complex tone for sound measurement by the apparatus.

### Claim 6 (depends on 5)

The method of claim 5, wherein generating a complex tone for sound measurement includes:
generating a complex test tone with frequencies separated by 50 Hz.

### Claim 7 (depends on 5)

The method of claim 5, wherein generating a complex test tone for sound measurement includes:
generating a complex test tone with frequencies at or above 100 Hz and at or below 16000 Hz.

### Claim 8 (depends on 1)

The method of claim 1, further comprising generating a swept tone for sound measurement by the apparatus.

### Claim 9 (depends on 1)

The method of claim 1, further comprising:
outputting the estimated sound pressure level at the tympanic membrane from the corrected output on a display device.

### Claim 10

An apparatus for measuring sound pressure level of sound in an ear canal at a tympanic membrane, comprising:
an audio output device to play the sound;
a microphone configured to receive the sound in the ear canal at a first distance from the tympanic membrane and to provide a signal based on the received sound; and
a processor executing instructions configured to:
perform frequency analysis on the signal and determine output as a function of frequency;
determine a null frequency of a minima of the output according to a single measurement at the first distance;
calculate a second distance equal to a quarter wavelength of a wave at the null frequency;
retrieve a previously generated correction factor associated with the second distance, and
apply the correction factor to the output to generate a corrected output related to an estimated sound pressure level at the tympanic membrane.

### Claim 11 (depends on 10)

The apparatus of claim 10, wherein the processor is programmed to perform an FFT on the signal.

### Claim 12 (depends on 10)

The apparatus of claim 10, wherein the correction factor is a function of width of the minima.

### Claim 13 (depends on 10)

The apparatus of claim 10, wherein the correction factor is a function of depth of the minima.

### Claim 14 (depends on 10)

The apparatus of claim 10, wherein the sound is a complex tone.

### Claim 15 (depends on 14)

The apparatus of claim 14, wherein the complex is a complex tone with frequencies at or above 100 Hz and at or below 16000 Hz.

### Claim 16 (depends on 14)

The apparatus of claim 14, wherein the complex is a complex tone with frequencies separated by 50 Hz.

### Claim 17 (depends on 10)

The apparatus of claim 10, wherein the sound is a swept tone.

### Claim 18 (depends on 10)

The apparatus of claim 10, further comprising a display device to present the estimated sound pressure level at the tympanic membrane from the corrected output.

### Claim 19 (depends on 10)

The apparatus of claim 10, further comprising a probe, wherein the probe is attached to the audio output device.

### Claim 20 (depends on 10)

The apparatus of claim 10, wherein the processor is configured to send the sound wirelessly to the audio output device.