Prosecution Insights
Last updated: April 19, 2026
Application No. 18/285,946

Tone Detection in Hearing Device Audio Signals

Non-Final OA §103
Filed
Oct 06, 2023
Examiner
BEKEE, CHIMEZIE EZERIWE
Art Unit
2691
Tech Center
2600 — Communications
Assignee
Eargo Inc.
OA Round
2 (Non-Final)
69%
Grant Probability
Favorable
2-3
OA Rounds
2y 8m
To Grant
99%
With Interview

Examiner Intelligence

Grants 69% — above average
69%
Career Allow Rate
11 granted / 16 resolved
+6.8% vs TC avg
Strong +33% interview lift
Without
With
+33.3%
Interview Lift
resolved cases with interview
Typical timeline
2y 8m
Avg Prosecution
27 currently pending
Career history
43
Total Applications
across all art units

Statute-Specific Performance

§101
1.6%
-38.4% vs TC avg
§103
67.7%
+27.7% vs TC avg
§102
18.2%
-21.8% vs TC avg
§112
6.8%
-33.2% vs TC avg
Black line = Tech Center average estimate • Based on career data from 16 resolved cases

Office Action

§103
DETAILED ACTION Notice of Pre-AIA or AIA Status The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . Claim Rejections - 35 USC § 103 1. In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status. The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action: A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made. 2. Claim(s) 1-3, 7-17, and 20 are rejected under 35 U.S.C. 103 as being unpatentable over Jensen et al. (U.S. Pub. No. 2017/0230765 A1, hereinafter "Jensen") in view of Pilati et al. (U.S. Pub. No. 2009/0222264 A1, hereinafter "Pilati"), and further in view of Park et al. (U.S. Pub. No. 2015/0172815 A1, hereinafter "Park"). Regarding Claim 1, Jensen teaches a method of signal processing an audio signal in a hearing device to determine whether the signal is tonal (audio signal processing method of a hearing aid to determine whether the signal is tonal, Para. [0159]), the method comprising: converting the signal at each of a series of successive time windows into samples in the frequency domain across multiple subbands (time window signals are converted into samples in the frequency domain across multiple sub-bands, Figs. 1A and 1B, Paras. [0165]-[0168]). Jensen fails to explicitly teach calculating for at least one of the subbands a normalized cross-correlation between two different samples in the same subband; and comparing a metric resulting from said calculating to a predetermined threshold to provide a measure of whether the signal is tonal; wherein the signal is considered to be tonal in the frequency of the subband when the metric is greater than or equal to the predetermined threshold and the signal is considered to be not tonal in the frequency of the subband when the metric is less than the predetermined threshold. However, Pilati teaches calculating for at least one of the subbands a normalized cross-correlation between two different samples in the same subband (a normalized cross correlation is calculated between sub-band samples generated for the particular frequency sub-band, Para. [0093]). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the audio signal processing method (as taught by Jensen) to include the calculation of a normalized cross correlation between samples of the same subband (as taught by Pilati). Doing so, matching error between the sub-band samples can be determined allowing for more precise detection of features or delays (Pilati Para. [0093]). However, Park teaches comparing a metric resulting from said calculating to a predetermined threshold to provide a measure of whether the signal is tonal (normalized correlation is compared to a predetermined threshold to provide a measure of tonal signal, Para. [0055]); wherein the signal is considered to be tonal in the frequency of the subband when the metric is greater than or equal to the predetermined threshold and the signal is considered to be not tonal in the frequency of the subband when the metric is less than the predetermined threshold (the signal is determined to be tonal when the normalized correlation is greater than a predetermined threshold and considered not tonal when the normalized correlation is below the predetermined threshold, Para. [0055]). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the audio signal processing method (as taught by Jensen in view of Pilati) to include the comparing a metric to a predetermined threshold and signal considered as tonal or not if metric is greater or less than the predetermined threshold (as taught by Park). Doing so, helps detect signal similarity and filters noise. Regarding Claim 2, Jensen in view of Pilati, and further in view of Park teach wherein said calculating and comparing are performed for each of a plurality of the multiple subbands (Pilati, normalized cross correlation is calculated for multiple sub-bands, Paras. [0067]-[0069]; Park, comparing of a metric resulting from said calculating to a predetermined threshold to provide a measure of whether the signal is tonal, Para. [0055]). Regarding Claim 3, it is similarly rejected as Claim 2. Regarding Claim 7, Jensen in view of Pilati, and further in view of Park teach wherein when a signal is considered to be tonal, said method further comprises: reducing a gain of the signal in the subband where the tonal signal is considered to be (Park, control circuitry 220 may reduce a gain when feedback is occurring, Para. [0056]). Regarding Claim 8, Jensen in view of Pilati, and further in view of Park teach wherein when a signal is considered to be tonal, said method further comprises: providing the tonal signal to a feedback cancellation system configured to determine whether the tonal signal is feedback (Park, control circuitry 220 may reduce a gain when feedback is occurring, Para. [0056]). Regarding Claim 9, Jensen in view of Pilati, and further in view of Park teach wherein the hearing device is a hearing aid (Jensen, hearing aid (HD), Figs. 8A, 9, Para. [0159]). Regarding Claim 10, Jensen in view of Pilati, and further in view of Park teach wherein the hearing aid is a completely-in-the-canal (CIC) hearing aid (Jensen, hearing aid is a CIC unit, Para. [0130]). Regarding Claim 11, Jensen teaches a hearing device (hearing aid (HD), Fig. 8A, Para. [0247]), comprising: a microphone (microphone providing input signal y', Fig. 8A, Para. [0247]); a receiver (a loudspeaker connected to output of signal processor (SPU), Fig. 8A, Para. [0247]); and a processor connected to said microphone and said receiver (signal processor (SPU) connected to microphone and loudspeaker, Fig. 8A, Para. [0247]), said processor configured to receive an audio signal from said microphone and process the audio signal and said receiver configured to provide an output signal to a user (signal processor (SPU) receives audio signal from microphone, processes the audio signal and outputs the processed audio to the loudspeaker, Fig. 8A, Para. [0247]), the processor further configured to: convert the signal at each of a series of successive time windows into samples in the frequency domain across multiple subbands (time window signals are converted into samples in the frequency domain across multiple sub-bands, Figs. 1A and 1B, Paras. [0165]-[0168]). Jensen fails to explicitly teach calculate for at least one of the subbands a normalized cross-correlation between two different samples in the same subband; and compare a metric resulting from the calculation of the normalized cross-correlation to a predetermined threshold to provide a measure of whether the signal is tonal; wherein the signal is considered to be tonal in the frequency of the subband when the metric is greater than or equal to the predetermined threshold and the signal is considered to be not tonal in the frequency of the subband when the metric is less than the predetermined threshold. However, Pilati teaches calculate for at least one of the subbands a normalized cross-correlation between two different samples in the same subband (a normalized cross correlation is calculated between sub-band samples generated for the particular frequency sub-band, Para. [0093]). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the audio signal processing method (as taught by Jensen) to include the calculation of a normalized cross correlation between samples of the same subband (as taught by Pilati). Doing so, matching error between the sub-band samples can be determined allowing for more precise detection of features or delays (Pilati Para. [0093]). However, Park teaches compare a metric resulting from the calculation of the normalized cross-correlation to a predetermined threshold to provide a measure of whether the signal is tonal (normalized correlation is compared to a predetermined threshold to provide a measure of tonal signal, Para. [0055]); wherein the signal is considered to be tonal in the frequency of the subband when the metric is greater than or equal to the predetermined threshold and the signal is considered to be not tonal in the frequency of the subband when the metric is less than the predetermined threshold (the signal is determined to be tonal when the normalized correlation is greater than a predetermined threshold and considered not tonal when the normalized correlation is below the predetermined threshold, Para. [0055]). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the audio signal processing method (as taught by Jensen in view of Pilati) to include the comparing a metric to a predetermined threshold and signal considered as tonal or not if metric is greater or less than the predetermined threshold (as taught by Park). Doing so, helps detect signal similarity and filters noise. Regarding Claim 12, it is similarly rejected as Claim 9. Regarding Claim 13, it is similarly rejected as Claim 10. Regarding Claim 14, it is similarly rejected as Claim 7. Regarding Claim 15, it is similarly rejected as Claim 8. Regarding Claim 16, it is similarly rejected as Claim 2. Regarding Claim 17, it is similarly rejected as Claim 2. Regarding Claim 20, it is similarly rejected as Claim 11. 3. Claim(s) 4 and 18 are rejected under 35 U.S.C. 103 as being unpatentable over Jensen et al. (U.S. Pub. No. 2017/0230765 A1, hereinafter "Jensen") in view of Pilati et al. (U.S. Pub. No. 2009/0222264 A1, hereinafter "Pilati") in view of Park et al. (U.S. Pub. No. 2015/0172815 A1, hereinafter "Park"), and further in view of Melkote et al. (U.S. Pub. No. 2015/0380000 A1, hereinafter "Melkote"). Regarding Claim 4, Jensen in view of Pilati, and further in view of Park teaches wherein said calculating step is iterated for successive samples (Pilati, the calculating step is repeated for consecutive samples, Paras. [0067]-[0069]). Jensen in view of Pilati, and further in view of Park fail to explicitly teach wherein said comparing step is performed relative to an average of the results from the iterated calculation steps. However, Melkote teaches calculating an average of normalized cross correlation (averaging normalized cross-correlation across all of the individual channel frequency bands, Para. [0384]). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the audio signal processing method (as taught by Jensen in view of Pilati, and further in view of Park) to include the calculate an average of normalized cross correlation which can be used in the comparing step (as taught by Melkote). Doing so improves detection reliability and provides a standardized measure of similarity robust to changes in signal amplitude and noise. Regarding Claim 18, it is similarly rejected as Claim 4. 4. Claim(s) 5 is rejected under 35 U.S.C. 103 as being unpatentable over Jensen et al. (U.S. Pub. No. 2017/0230765 A1, hereinafter "Jensen") in view of Pilati et al. (U.S. Pub. No. 2009/0222264 A1, hereinafter "Pilati") in view of Park et al. (U.S. Pub. No. 2015/0172815 A1, hereinafter "Park"), further in view of Jensen et al. (U.S. Pat. No. 5450490 A, hereinafter "Jensen'490"). Regarding Claim 5, Jensen in view of Pilati, and further in view of Park fail to explicitly teach wherein there is no time overlap corresponding to the two different samples in the frequency or joint time-frequency domain. However, Jensen'490 teaches wherein there is no time overlap corresponding to the two different samples in the frequency or joint time-frequency domain (audio signal undergoes frequency range separation which can be carried out as a fast fourier transform without temporal overlap, Fig. 3, Col. 13, Lns. 9-23). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the audio signal processing method (as taught by Jensen in view of Pilati, and further in view of Park) to include no time overlap of audio samples transformed into frequency sub-bands (as taught by Jensen). Doing so, produces successive frequency bands having a predetermined frequency width and to mask out tonal signals making them inaudible (Jensen Col. 13, Lns. 9-34). 5. Claim(s) 6 and 19 are rejected under 35 U.S.C. 103 as being unpatentable over Jensen et al. (U.S. Pub. No. 2017/0230765 A1, hereinafter "Jensen") in view of Pilati et al. (U.S. Pub. No. 2009/0222264 A1, hereinafter "Pilati") in view of Park et al. (U.S. Pub. No. 2015/0172815 A1, hereinafter "Park"), and further in view of Pralea ("Fixed-point Implementation of a Coherence-based Double-talk Detector for Line Echo Cancelers" - August 29, 2017). Regarding Claim 6, Jensen in view of Pilati, and further in view of Park fail to explicitly teach comprising improving processing efficiency of said calculating step by using at least one of count sign bits (CSB), count leading bits (CLB) or log2 approximation of absolute value. However, Pralea teaches using count leading bits (for FFT outputs at the same frequency, normalization across windows is applied (different scaling factors per different FFT bins) by implementing scaling loops using Count Leading Bits CLB instruction that counts the leading zeros or ones according to bit 39 of source data register, relative to bit 31, Pg. 1, Col. 2, Sec. II thru Pg. 3, Col. 1, Para. 2). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the audio signal processing method (as taught by Jensen in view of Pilati, and further in view of Park) to include applying a count leading bits instructions (as taught by Pralea). Doing so, increases the computational speed and efficiency leading to reduced load and lowing power consumption. Regarding Claim 19, it is similarly rejected as Claim 6. Response to Arguments 6. Applicant’s arguments with respect to claim(s) 1-5, 7-18, and 20 have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument. Claims 1-3, 7-17, and 20 have been rejected on a new ground of rejection under 35 U.S.C. 103 as being unpatentable over Jensen in view of Pilati, and further in view of Park. The rejections of Claims 1-3, 7-17, and 20 under 35 U.S.C. 103 as being unpatentable over Jensen in view of Pilati, and further in view of Park are maintained. Claims 4 and 18 have been rejected on a new ground of rejection under 35 U.S.C. 103 as being unpatentable over Jensen in view of Pilati in view of Park, and further in view of Melkote. The rejections of Claims 4 and 18 under 35 U.S.C. 103 as being unpatentable over Jensen in view of Pilati in view of Park, and further in view of Melkote are maintained. Claim 5 has been rejected on a new ground of rejection under 35 U.S.C. 103 as being unpatentable over Jensen in view of Pilati in view of Park, and further in view of Jensen'490. The rejection of Claim 5 under 35 U.S.C. 103 as being unpatentable over Jensen in view of Pilati in view of Park, and further in view of Jensen'490 is maintained. 7. Applicant’s arguments, see pages 16-17, filed December 05, 2025, with respect to the rejection(s) of claim(s) 6 under 35 U.S.C. 103 as being unpatentable over Ebenezer in view of Pralea have been fully considered and are persuasive. Therefore, the rejection has been withdrawn. However, upon further consideration, a new ground(s) of rejection is made in view of 35 U.S.C. 103 as being unpatentable over Jensen in view of Pilati in view of Park, and further in view of Pralea. The rejection of Claim 6 under 35 U.S.C. 103 as being unpatentable over Jensen in view of Pilati in view of Park, and further in view of Pralea is maintained. Conclusion 8. Any inquiry concerning this communication or earlier communications from the examiner should be directed to CHIMEZIE E BEKEE whose telephone number is (571)272-0202. The examiner can normally be reached M-F 7.30-5. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Duc Nguyen can be reached at 571-272-7503. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /CHIMEZIE EZERIWE BEKEE/Examiner, Art Unit 2691 /DUC NGUYEN/Supervisory Patent Examiner, Art Unit 2691
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Prosecution Timeline

Oct 06, 2023
Application Filed
Sep 03, 2025
Non-Final Rejection — §103
Dec 05, 2025
Response Filed
Dec 17, 2025
Applicant Interview (Telephonic)
Dec 17, 2025
Examiner Interview Summary
Feb 19, 2026
Non-Final Rejection — §103 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

2-3
Expected OA Rounds
69%
Grant Probability
99%
With Interview (+33.3%)
2y 8m
Median Time to Grant
Moderate
PTA Risk
Based on 16 resolved cases by this examiner. Grant probability derived from career allow rate.

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