Semi-adaptive active noise cancellation headphones

Active noise cancellation (ANC) headphones are becoming increasingly important as they can effectively attenuate perceived ambient noise. Fixed filters are commonly applied in commercially available ANC headphones due to their robustness. However, they are not capable of adapting to changes that occur in dynamic environments, resulting in degraded ANC performance. In contrast, adaptive filters are able to update the ANC filters to compensate for noise in dynamic environments, but large estimation errors can occur due to a sudden change in direction/type of noise or secondary path. Some studies have suggested an ANC system by combining fixed and adaptive filters. Based on this mechanism, we propose a semi-adaptive ANC system in which the fixed and adaptive filters are weighted in real-time. Initially, the weighting for the fixed filter dominates the whole system to ensure the robustness of the ANC system. Then, the residual error provided by the adaptive filter is simulated and compared to the real measured one to determine the relative weighting between the fixed and adaptive filters. In this study, this approach is applied to a feedback ANC system. Simulation results show that our proposed approach achieves high noise attenuation performance while maintaining robustness with time-varying secondary paths.

Download Full-text

Development of an Active Noise Cancellation Hearing Protector: How Can Passive Attenuation Be Retained?

Noise & Vibration Worldwide ◽

10.1260/095745605775220998 ◽

2005 ◽

Vol 36 (11) ◽

pp. 9-17 ◽

Cited By ~ 1

Author(s):

Mika Oinonen ◽

Harri Raittinen ◽

Markku Kivikoski

Keyword(s):

Low Frequency ◽

Noise Cancellation ◽

Noise Attenuation ◽

Active Noise Cancellation ◽

Analog Electronics ◽

Active Noise ◽

Measurement Results ◽

Proper Design ◽

Hearing Protector ◽

Passive Hearing

The modest low-frequency attenuation of the conventional passive hearing protector can be improved electronically by active noise cancellation techniques. This paper presents the theory and some of the actual limitations of an active noise cancellation hearing protector. Three prototypes with similar types of controller, but with different mechanical construction were made and their performance was measured. The electronics of the system were implemented using analog electronics and feedback construction. The measurement results were compared with the results of an equivalent passive hearing protector with no internal electronics and with an intact earcup. The results show that the integration of the controller inside the earcups degrades the passive attenuation of the hearing protector at frequencies below 200 Hz. With proper design, an active noise cancellation hearing protector can still have 15 dB more noise attenuation at 100 - 200 Hz range than an equivalent passive hearing protector.

Download Full-text

Active Noise Cancellation for IoT-Driven Electronic Stethoscope: A Comparative Study of Adaptive Filters

Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering - Forthcoming Networks and Sustainability in the IoT Era ◽

10.1007/978-3-030-69431-9_2 ◽

2021 ◽

pp. 11-24

Author(s):

Erdinc Turk ◽

Umit Deniz Ulusar ◽

Guner Ogunc ◽

Murat Canpolat ◽

Muhittin Yaprak

Keyword(s):

Comparative Study ◽

Adaptive Filters ◽

Noise Cancellation ◽

Electronic Stethoscope ◽

Active Noise Cancellation ◽

Active Noise

Download Full-text

Noise Attenuation Effects on Speech Recognition of Cochlear Implant Users Inside Helicopters

Aerospace Medicine and Human Performance ◽

10.3357/amhp.5884.2021 ◽

2021 ◽

Vol 92 (11) ◽

pp. 880-885

Author(s):

Juliana Maria Araujo Caldeira ◽

Maria Valéria ◽

Schmidt Goffi-Gomez ◽

Rui Imamura ◽

Ricardo Ferreira Bento

Keyword(s):

Speech Recognition ◽

Cochlear Implant ◽

Noise Cancellation ◽

Civil Aviation ◽

Noise Attenuation ◽

Background Condition ◽

Radio System ◽

Speech Processor ◽

Active Noise Cancellation ◽

Active Noise

BACKGROUND: The speech recognition levels of cochlear implant (CI) users are still incompatible with ICAO hearing requirements for civil aviation pilots testing in the noisy background condition of the helicopter cockpit. In this study, we evaluated noise attenuation effects on speech recognition in the same background condition.METHODS: The study involved the evaluation of 12 Portuguese-speaking CI users with post-lingual deafness and with a pure tone average up to 35 dB HL between 500 and 2000 Hz and up to 50 dB at 3000 Hz on at least one of the ears, and of three normal hearing pilots (controls). We performed speech recognition tests using sentences, numbers, and disyllables for all participants through the VHF radio. The assessment took place inside a helicopter with engine on, using three setups: 1) with headset without the active noise cancellation; 2) activating the noise cancellation system of the headset itself; and 3) connecting the speech processor directly to the helicopter radio system.RESULTS: The headset active noise-cancellation improved only the recognition of sentences. The direct connection system compared to the headset without anti-noise attenuation significantly improved all the recognition tests. The median for numbers was 90%, but the best score for disyllables recognition was 56%.DISCUSSION: The noise attenuation resources proposed in this study improved the CI users speech recognition when exposed to the noisy helicopter cockpit. However, speech recognition of CI users still did not meet the standards of ICAO, which requires at least 80% for understanding disyllables in the speech in noise test.Caldeira JMA, Goffi-Gomez MVS, Imamura R, Bento RF. Noise attenuation effects on speech recognition of cochlear implant users inside helicopters. Aerosp Med Hum Perform. 2021; 92(11):880-885.

Download Full-text

Simulation of LMS based adaptive noise cancellation using Labview

INTER-NOISE and NOISE-CON Congress and Conference Proceedings ◽

10.3397/in-2021-2128 ◽

2021 ◽

Vol 263 (4) ◽

pp. 2405-2411

Author(s):

Maja Anachkova ◽

Simona Domazetovska ◽

Zlatko Petreski ◽

Viktor Gavriloski

Keyword(s):

Communication Systems ◽

Adaptive Filters ◽

Noise Cancellation ◽

Lms Algorithm ◽

Destructive Interference ◽

Least Mean Square ◽

Audio File ◽

Active Noise Cancellation ◽

Active Noise ◽

Before And After

The audio signals processed in the signal measurement systems are inevitably susceptible to unwanted noise which significantly affects the quality of the signal and the overall performance of the signal communication systems. Due to its' random and unpredictable nature, the amount of noise in signals has proven to be a significant issue in designing these systems and recently has been a trending research topic. In this regard, the active noise cancellation method has proven to be an effective technique for eliminating the noise effects on signal processing. The concept of active noise cancellation is based on the application of adaptive filters and algorithms proposed to reduce the signal corruption and distortion caused by the noise due to the principle of destructive interference. In this paper a simulation model of active noise reduction technique using the LMS (Least Mean Square) algorithm in Labview is presented. The purpose of the work is to investigate the noise cancellation effect on a recorded audio file in terms of analyzing the audio file before and after filtering out the noise by using the LMS algorithm and discuss the results thereof.

Download Full-text

Investigation of aircrew noise exposure levels and hearing protection solutions in helicopter cabin

Journal of Intelligent Material Systems and Structures ◽

10.1177/1045389x16667553 ◽

2016 ◽

Vol 28 (8) ◽

pp. 1050-1058

Author(s):

Yong Chen ◽

Sebastian Ghinet ◽

Andrew Price ◽

Viresh Wickramasinghe ◽

Anant Grewal

Keyword(s):

Air Force ◽

Noise Exposure ◽

Low Frequency ◽

Noise Cancellation ◽

Frequency Noise ◽

Noise Attenuation ◽

Active Noise Cancellation ◽

Cabin Noise ◽

Active Noise ◽

Royal Canadian Air Force

High noise levels in the helicopter cabin adversely affect aircrew communication and reduce comfort in the short-term and may lead to hearing loss in the long-term if flight helmets cannot provide sufficient protection to the aircrew. A cabin noise exposure survey has been performed on a Royal Canadian Air Force CH-147F Chinook heavy lift helicopter to evaluate the noise environment and noise protection performance of the flight helmet. Investigation results showed that the low-frequency noise attenuation provided by the Royal Canadian Air Force flight helmet was marginal in high-speed flight conditions that generate loud cabin noise. Therefore, in-canal earphone integrated with active noise cancellation capability was investigated to provide enhanced noise protection and improve clarity in voice communication. Simulation and proof-of-concept test results verified that active noise cancellation in-canal earphones can serve as a feasible technical solution to provide enhanced noise attenuation to mitigate the low-frequency N/rev tonal noise generated by the aerodynamic pressure from the helicopter rotor blades.

Download Full-text