Proof-of-Concept Design for MPP Acoustic Absorbers with Elements of Art

A micro-perforated plate or panel (MPP) is a device used to absorb sound. It consists of a thin flat plate made from several different materials with small holes and a back cavity. Several reported modifications and enhancements to the original design of the MPP acoustic absorber were modified by the holes or the back-cavity shape and sizes following the original idea. The present study attempts to artistically beautify the MPP acoustic absorbers by incorporating dotted arts into the design of MPP. The perforation for micro-perforated panels could be dotted arts with a perforation size smaller than 1 mm for enhanced acoustic absorption performance in the form of various artistic designs. Small LED lights could be placed inside the acoustic chamber to create the color lights emanating from the perforations instead of dots with different colors. Several MPP incorporated artistic designs of dotted patterns were presented and their acoustic absorption performance was analyzed using impedance tube in this paper.

Assessment of an acoustic chamber for testing structure-borne sound transmission in a double-panel assembly

An acoustic chamber was designed for testing structure-borne sound transmission in a double-panel assembly induced by point connectors. Several vibration isolators were tested and the overall effects on the noise transmitted through the assembly were predicted by establishing the link between the vibratory acceleration level (VAL) and the sound pressure level (SPL). A detailed assessment of the acoustic chamber showed that a major modification of the double-panel assembly is required before the acoustic performance of this assembly could be evaluated directly using insertion loss (IL) measurements where the sound pressure level (SPL) difference is the performance indicator. This thesis describes the assessment findings and retrofitting options. It is concluded that adjustments to the VAL-to-SPL relation are required to account for distance, radiation efficiency, and room effects. Further adjustments to the acoustic chamber are required to enhance its performance.

Assessment of an acoustic chamber for testing structure-borne sound transmission in a double-panel assembly

An acoustic chamber was designed for testing structure-borne sound transmission in a double-panel assembly induced by point connectors. Several vibration isolators were tested and the overall effects on the noise transmitted through the assembly were predicted by establishing the link between the vibratory acceleration level (VAL) and the sound pressure level (SPL). A detailed assessment of the acoustic chamber showed that a major modification of the double-panel assembly is required before the acoustic performance of this assembly could be evaluated directly using insertion loss (IL) measurements where the sound pressure level (SPL) difference is the performance indicator. This thesis describes the assessment findings and retrofitting options. It is concluded that adjustments to the VAL-to-SPL relation are required to account for distance, radiation efficiency, and room effects. Further adjustments to the acoustic chamber are required to enhance its performance.

Using a cochlear implant processor as contralateral routing of signals device in unilateral cochlear implant recipients

Purpose In unilateral cochlear implant (CI) recipients, a contralateral routing of signals (CROS) device enables to receive auditory information from the unaided side. This study investigates the feasibility as well as subjective and objective benefits of using a CI processor as a CROS device in unilateral CI recipients. Methods This is a single-center, prospective cohort study. First, we tested the directionality of the CROS processor in an acoustic chamber. Second, we examined the difference of speech perception in quiet and in noise in ten unilateral CI recipients with and without the CROS processor. Third, subjective ratings with the CROS processor were evaluated according to the Client Oriented Scale of Improvement Questionnaire. Results There was a time delay between the two devices of 3 ms. Connection of the CROS processor led to a summation effect of 3 dB as well as a more constant amplification along all azimuths. Speech perception in quiet showed an increased word recognition score at 50 dB (mean improvement 7%). In noise, the head shadow effect could be mitigated with significant gain in speech perception (mean improvement 8.4 dB). This advantage was reversed in unfavorable listening situations, where the CROS device considerably amplified the noise (mean: – 4.8 dB). Subjectively, patients who did not normally wear a hearing aid on the non-CI side were satisfied with the CROS device. Conclusions The connection and synchronization of a CI processor as a CROS device is technically feasible and the signal processing strategies of the device can be exploited. In contra-laterally unaided patients, a subjective benefit can be achieved when wearing the CROS processor.

Multichannel acoustic source and image dataset for the cocktail party effect in hearing aid and implant users

The Cocktail Party Effect refers to the ability of the human sense of hearing to extract a specific target sound source from a mixture of background noises in complex acoustic scenarios. The ease with which normal hearing people perform this challenging task is in stark contrast to the difficulties that hearing-impaired subjects face in these situations. To help patients with hearing aids and implants, scientists are trying to imitate this ability of human hearing, with modest success so far. To support the scientific community in its efforts, we provide the Bern Cocktail Party (BCP) dataset consisting of 55938 Cocktail Party scenarios recorded from 20 people and a head and torso simulator wearing cochlear implant audio processors. The data were collected in an acoustic chamber with 16 synchronized microphones placed at purposeful positions on the participants’ heads. In addition to the multi-channel audio source and image recordings, the spatial coordinates of the microphone positions were digitized for each participant. Python scripts were provided to facilitate data processing.

Mechanical Designing of Acoustic Chamber Based Muffler for Sound Reduction

Sound of exhaust system makes a substantial contribution to the interior as well as exterior noise of automobiles. Accurate prediction and control of noise from automobiles is of significant importance in automotive exhaust system design. When it comes into the term of acoustic performance there are several parameters that describe the performance of a muffler, the Transmission Loss (TL) being the most popular one for validating an analytical model. Acoustic characteristics of silencers filled with fibrous material are also studied.