Wireless Microphone Systems Research Articles

PROTOCOLS FOR COLLECTING CONVERSATIONAL LANGUAGE IN PERSONS WITH DEMENTIA

Abstract We describe first-of-its-kind protocols for collecting spontaneous conversations in persons with dementia living in a community through conversation elicitation tools twice a month over six months. We also describe the preliminary feasibility of the protocol deployment in the first enrolled participants over the first month of data collection. Participants were recruited from the University of Washington ADRC registry. The audio was captured using RODE wireless microphone system. Four conversational elicitation techniques were used: 1) reminiscence using personal photographs; 2) reminiscence using generic historical images; 3) picture description test from neurocognitive batteries; 4) open-ended questions about daily activities. Health measures included Cornell Scale for Depression in Dementia (CSDD), Clinical Dementia Rating (CDR), and Clinical Frailty Scale (CFS). Four male and two female participants (average age 75) were recruited. Average health measures at baseline were CDR = 2, suggesting moderate dementia; CSDD=7, suggesting depressive symptoms, CFS=5, suggesting mild frailty. At baseline, the tasks’ average conversation time in seconds was as follows: daily activities =528; personal reminiscence=443; historical reminiscence =227; picture description =192. The corresponding average times for the subsequent home visits were 917; 518; 474, and 280 at visit 1 and 525; 767; 629, and 311 at visit 2. We established the feasibility of collecting conversational speech in this population. Participants seemed more interested in conversations focused on daily activities and personal pictures than general topics. There was an increase in the duration of conversations over time, which might be related to participants’ greater familiarity with the study protocol and data collectors.

A Qualitative Investigation of Clients, Significant Others, and Clinicians' Experiences of Using Wireless Microphone Systems to Manage Hearing Impairment.

This study aimed to explore the perceptions and experiences of adults with hearing impairment (HI), their significant others (SOs), and clinicians regarding the use and provision of wireless microphone systems (WMS). A qualitative descriptive methodology was used, with a total of 43 participants across three groups: (1) 23 adults with HI who used WMS; (2) 7 SOs of adults who used WMS; and (3) 13 clinicians who provided WMSs to adults with HI. Participants completed an individual semi-structured in-depth interview to explore their experiences, with the data analysed using thematic analysis. The analysis revealed five themes encompassing the perceptions and experiences of WMSs: (1) with experience and clear expectations, users believe that WMS can make a difference; (2) the trial and decision-making process is important; (3) clients' experiences using WMS; (4) issues with WMS and technology; and (5) users require ongoing training and support to use WMS. These findings highlight the complexities of providing and using WMS with adults with HI. However, clients, SOs, and clinicians all reported that, with appropriate experience, expectations, training, and support, WMS can make a real difference in listening and communicating in different situations. There is also an opportunity to involve SOs more throughout the rehabilitation process.

Design and verification of a measurement setup for wireless remote microphone systems (WRMSs)

Objective This work presents the design and verification of a simplified measurement setup for wireless remote microphone systems (WRMSs), which has been incorporated into guidelines of the European Union of Hearing Aid Acousticians (EUHA). Design Three studies were conducted. First, speech intelligibility scores within the simplified setup were compared to that in an actual classroom. Second, different WRMSs were compared in the simplified setup, and third, normative data for normal-hearing people with and without WRMS were collected. Study sample The first two studies include 40 older hearing impaired and the third study 20 young normal-hearing adults. Results Speech intelligibility with WRMS was not different across actual classroom and simplified setup. An analog omnidirectional WRMS showed poorer speech intelligibility and poorer quality ratings than digital WMRSs. The usage of a WRMS in the simplified setup resulted in significantly higher speech intelligibility across all tested background noise levels. Conclusions Despite being a simplified measurement setup, it realistically emulates a situation where people are listening to speech in noise from a distance, such as in a classroom or meeting room. Hence, with standard audiological equipment, the individual benefit of WRMSs can be measured and experienced by the user in clinical practice.

Application of Digital Remote Wireless Microphone Technology in Single-Sided Deaf Cochlear Implant Recipients.

Previous research showed benefits of remote wireless technology in bilaterally moderate- to-severe hearing-impaired participants provided with hearing aid(s), cochlear implant(s) (CIs), or bimodal devices as well as in single-sided deaf (SSD) cochlear implant recipients (with CI from Cochlear™) and normal-hearing (NH) participants. To evaluate the effect of the digital remote wireless microphone system, Roger™, on speech recognition at different levels of multisource noise in SSD CI recipients using MED-EL CI sound processor OPUS 2. Outcomes were assessed as a function of the listening condition (NH only, NH + CI, NH + CIRog, NHRog + CI, and NHRog + CIRog), Roger™ receiver type (Roger™ Focus for NH; Roger™ Xand Roger™ MyLink for CI) and accessory mixing ratio. Eleven adult, SSD participants aided with CI from MED-EL. Speech recognition in noise was assessed in two no-Roger™ conditions, one Roger™ X condition, and two Roger™ MyLink conditions. For the Roger™ X and no-Roger™ conditions, speech recognition was tested at 60.3 dB(A) with the Oldenburg Sentence Test in classroom noise at levels of 55, 65, and 75 dB(A). For the two Roger™ MyLink conditions, speech recognition at 60.3 dB(A) was measured at a noise level of 75 dB(A). Roger™ X was assessed with an accessory mixing ratio of 1:1 (summation of unattenuated microphone and audio accessory input). For Roger™ MyLink, two accessory mixing ratios were investigated, MT (1:1, summation of unattenuated microphone and telecoil input) and T with maximum attenuation of microphone input. Speech recognition at higher noise levels (65 and 75 dB(A)) improved significantly with Roger™ in both unilateral use conditions (NH + CIRog and NHRog + CI) as well as bilateral use condition (NHRog + CIRog). Both the bilateral application of Roger™ and the unilateral Roger™ application on the NH ear outperformed the Roger™ application on CI alone. There was no statistically significant effect of type of CI Roger™ receiver (Roger™ X or Roger™ MyLink) and the accessory mixing ratio (MT or T) on speech recognition. Speech recognition for distant speakers in multisource noise improved significantly with the application of Roger™ in SSD CI recipients. Both the unilateral Roger™ application on the NH ear or the CI as well as the bilateral Roger™ application can be recommended.

Speech Recognition in Noise in Single-Sided Deaf Cochlear Implant Recipients Using Digital Remote Wireless Microphone Technology.

Previous research in cochlear implant (CI) recipients with bilateral severe-to-profound sensorineural hearing loss showed improvements in speech recognition in noise using remote wireless microphone systems. However, to our knowledge, no previous studies have addressed the benefit of these systems in CI recipients with single-sided deafness. The objective of this study was to evaluate the potential improvement in speech recognition in noise for distant speakers in single-sided deaf (SSD) CI recipients obtained using the digital remote wireless microphone system, Roger. In addition, we evaluated the potential benefit in normal hearing (NH) participants gained by applying this system. Speech recognition in noise for a distant speaker in different conditions with and without Roger was evaluated with a two-way repeated-measures design in each group, SSD CI recipients, and NH participants. Post hoc analyses were conducted using pairwise comparison t-tests with Bonferroni correction. Eleven adult SSD participants aided with CIs and eleven adult NH participants were included in this study. All participants were assessed in 15 test conditions (5 listening conditions × 3 noise levels) each. The listening conditions for SSD CI recipients included the following: (I) only NH ear and CI turned off, (II) NH ear and CI (turned on), (III) NH ear and CI with Roger 14, (IV) NH ear with Roger Focus and CI, and (V) NH ear with Roger Focus and CI with Roger 14. For the NH participants, five corresponding listening conditions were chosen: (I) only better ear and weaker ear masked, (II) both ears, (III) better ear and weaker ear with Roger Focus, (IV) better ear with Roger Focus and weaker ear, and (V) both ears with Roger Focus. The speech level was fixed at 65 dB(A) at 1 meter from the speech-presenting loudspeaker, yielding a speech level of 56.5 dB(A) at the recipient's head. Noise levels were 55, 65, and 75 dB(A). Digitally altered noise recorded in school classrooms was used as competing noise. Speech recognition was measured in percent correct using the Oldenburg sentence test. In SSD CI recipients, a significant improvement in speech recognition was found for all listening conditions with Roger (III, IV, and V) versus all no-Roger conditions (I and II) at the higher noise levels (65 and 75 dB[A]). NH participants significantly benefited from the application of Roger in noise for higher levels, too. In both groups, no significant difference was detected between any of the different listening conditions at 55 dB(A) competing noise. There was also no significant difference between any of the Roger conditions III, IV, and V across all noise levels. The application of the advanced remote wireless microphone system, Roger, in SSD CI recipients provided significant benefits in speech recognition for distant speakers at higher noise levels. In NH participants, the application of Roger also produced a significant benefit in speech recognition in noise.

Perception of Auditory Distance in Normal-Hearing and Moderate-to-Profound Hearing-Impaired Listeners.

The auditory system allows the estimation of the distance to sound-emitting objects using multiple spatial cues. In virtual acoustics over headphones, a prerequisite to render auditory distance impression is sound externalization, which denotes the perception of synthesized stimuli outside of the head. Prior studies have found that listeners with mild-to-moderate hearing loss are able to perceive auditory distance and are sensitive to externalization. However, this ability may be degraded by certain factors, such as non-linear amplification in hearing aids or the use of a remote wireless microphone. In this study, 10 normal-hearing and 20 moderate-to-profound hearing-impaired listeners were instructed to estimate the distance of stimuli processed with different methods yielding various perceived auditory distances in the vicinity of the listeners. Two different configurations of non-linear amplification were implemented, and a novel feature aiming to restore a sense of distance in wireless microphone systems was tested. The results showed that the hearing-impaired listeners, even those with a profound hearing loss, were able to discriminate nearby and far sounds that were equalized in level. Their perception of auditory distance was however more contracted than in normal-hearing listeners. Non-linear amplification was found to distort the original spatial cues, but no adverse effect on the ratings of auditory distance was evident. Finally, it was shown that the novel feature was successful in allowing the hearing-impaired participants to perceive externalized sounds with wireless microphone systems.

Effects of Binaural Spatialization in Wireless Microphone Systems for Hearing Aids on Normal-Hearing and Hearing-Impaired Listeners.

Little is known about the perception of artificial spatial hearing by hearing-impaired subjects. The purpose of this study was to investigate how listeners with hearing disorders perceived the effect of a spatialization feature designed for wireless microphone systems. Forty listeners took part in the experiments. They were arranged in four groups: normal-hearing, moderate, severe, and profound hearing loss. Their performance in terms of speech understanding and speaker localization was assessed with diotic and binaural stimuli. The results of the speech intelligibility experiment revealed that the subjects presenting a moderate or severe hearing impairment better understood speech with the spatialization feature. Thus, it was demonstrated that the conventional diotic binaural summation operated by current wireless systems can be transformed to reproduce the spatial cues required to localize the speaker, without any loss of intelligibility. The speaker localization experiment showed that a majority of the hearing-impaired listeners had similar performance with natural and artificial spatial hearing, contrary to the normal-hearing listeners. This suggests that certain subjects with hearing impairment preserve their localization abilities with approximated generic head-related transfer functions in the frontal horizontal plane.

1-2 OFDM方式デジタルワイヤレスマイクにおける消失判定を用いたパルス干渉対策(第1部門 無線・光伝送)

1-2 OFDM方式デジタルワイヤレスマイクにおける消失判定を用いたパルス干渉対策(第1部門 無線・光伝送)

EMC performance measurements for professional wireless microphone systems

With shrinking spectral bandwidths and more intense use of the remaining frequency areas, the importance of good electromagnetic compatibility (EMC) performance of professional wireless microphone systems, as used by broadcasters, is increasing. A wireless microphone system consists of one or more pocket or handheld transmitters and usually the same amount of receivers. Both have to be immune against disturbances, and on the other hand they should not produce interferences. This paper deals with electromagnetic compatibility (EMC) performance tests of three analogue professional wireless microphone systems. The authors describe the complete measurement procedure using two different setups. These setups employ the pocket transmitter or the receiver as device under test (DUT). Different disturbance signals are used utilizing amplitude modulation (AM), frequency modulation (FM) or digital video broadcast-terrestrial (DVB-T). The audio quality of the transmission system is rated with the total harmonic distortion plus noise (THD+N). Additionally, the authors investigate intermodulations (third harmonic) caused by the transmitter. The results of all performance tests are extensively discussed.

Let's Make Them Cognitive Cognitive Radio Technology Applied to Professional Wireless Microphone Systems

In recent years, the ultra-high frequency (UHF) band from 470-862 MHz has been subject to several changes in frequency allocation, and a final decision for new services is still under discussion. Until 2010, this band was exclusively assigned to stations for terrestrial video broadcasting (DVB-T) [1]. The current demand for ever increasing data rates for mobile devices has led to changes in frequency range assignments. The key term digital dividend is frequently used by regulatory bodies and well-known in the cognitive radio community. In its first rollout, the band from 790-862 MHz was brought up for auction to mobile network operators in Germany [2]. The total revenue for 60 MHz of spectrum was ?3,575 billion [2], [3], which underlines the great market value of the radio spectrum.

Overview of Wireless Microphones—Part I: System and Technologies

Wireless microphones are indispensable to modern society. They are used worldwide by professionals and amateurs for such applications as live performances, electronic news gathering, and conference presentations. Due to the radio spectrum crunch, wireless microphones have become a hot topic of discussion and debate among television broadcasters, wireless microphone manufacturers, wireless network operators, and spectrum regulators. In order to keep wireless microphones operating well, it is necessary to give engineers, researchers, and regulators a comprehensive overview of wireless microphones in the aspects of technologies, spectrum requirements, and interference that may be experienced or generated by wireless microphones. This overview is divided into two parts. Part I provides an overview of typical wireless microphone system components, their performance requirements and technical parameters, and the technologies that are used in current wireless microphones. Part II focuses on the spectrum, sources of interference, and regulations surrounding wireless microphones.

Engineering the Integrated Clinical Environment Organizing Information in the Intensive Care Unit (ICU)

The overarching goal of this project is to develop engineering requirements for future information resources in the ICU. We describe a method and related instrumentation for collecting data about information requirements from a clinical team in situ. Video records are collected using three consumer-grade video cameras, augmented by a wireless microphone system. We combine the video/audio recordings into a single, synchronized record. A transcript is prepared, and then coded by a professional medical records coder, using the SNOMED CT coding scheme. The resulting record represents a coded stream of verbal utterances that is sufficiently precise to support systems engineering analysis.

4-5(1) 1.2 GHz帯ラジオマイクの開発

4-5(1) 1.2 GHz帯ラジオマイクの開発

On Primary User Coverage Probabilities and Faulty Cognitive Radios

In a cognitive radio (CR) network, the CR devices opportunistically communicate in the frequency bands occupied by the primary users in order to improve the spectral efficiency in these bands. By sensing the primary users, e.g., the television transmitter-receiver pairs and the wireless microphone systems, each CR device determines whether or not to operate in the band. The CR devices, due to erroneous sensing, either fail to detect the primary user, causing excessive interference at the primary users, or have a false-alarm, causing it to remain silent in a white-space band leading to poor spectrum utility. The impact of these imperfections on the primary user operations in terms of the coverage probability is characterized where the primary users and the CR devices are distributed according to independent homogeneous Poisson point processes on the plane.

20-1 低遅延デジタルラジオマイクシステムの開発(第20部門無線光伝送)

20-1 低遅延デジタルラジオマイクシステムの開発(第20部門無線光伝送)

Wireless Microphone System

Wireless Microphone System

Considerations on the frequency resource of professional wireless microphone systems

Abstract. This Paper presents the results of spectral observations in the UHF TV Bands IV and V from 470 MHz up to 862 MHz with focus on the TV-Channels 61 to 63 and 67 to 69. Concerning the discussions on \\citet{WRC} this frequency range is in great demand of several applications and is usually treated as a "white space" in the TV-Bands. According to typical scenarios, two different spectral loads will be presented considering the requirements of professional wireless microphone receivers with respect to in-band intermodulation.

Strategy for vocalization taken by FM bats during group flight measured by a wireless microphone system

The purpose of this study was to examine characteristics of vocalization emitted by an FM bat, Japanese pipistrelle bats (Pipistrellus abramus), during their group flight. We used a wireless microphone system, Telemike, to record vocalization of five bats while they were flying in a chamber with a companion (a paired flight). Echolocation pulses and returning echoes were measured by the Telemike (0.6g; including a battery) placed at the bats head. Simultaneously, a pair of high-speed video cameras were used to reconstruct their flight trajectories. The Telemike recorded not only their own pulses and echoes but also those of the companion bat. Overlapping of their own echolocation signals with those of the companion bat were analyzed. For one out of two bats, overlapping was always much lower than chance level on average. On the other hand, overlapping was around chance level for the other one. Their strategy appeared that one bat reduced the overlapping while the other did not. Communication calls were also recorded between two individuals during flight, which were never recorded when the bats flew alone. [The research supported by a grant to RCAST at Doshisha Univ. from MEXT and by the Innovative Cluster Creation Project promoted by MEXT]

Time-sharing acoustic stream analysis to recognize multiple objects in space by echolocating bats

Echolocating bats need to catch prey while they have to avoid obstacles and escape from their predators at the same time. Therefore, they have to perceive precise information about multiple objects from their surrounding space while they are flying. However, there are strong restrictions in the system; the neural system is too slow to perform real-time processing, and the bat has only one sound source emission and only two ears to receive echoes. The purpose of the present study was to investigate how echolocating bats perceive important information about different objects in space during their flight by analyzing acoustic characteristics of emitted pulses and returning echoes. Pulses and echoes of CF-FM and FM bats were recorded by a wireless telemetry microphone system (Telemike) on their head. In order to reconstruct their flight trajectory, a dual high speech video camera system was used. Obtained data showed multiple streams for temporal change in echo delay, Doppler-shift compensation, and echo intensity compensation. The present findings indicate that echolocating bats may adopt a time-sharing analysis, which is practically fast enough to recognize multiple objects in space during flight. [Work partly supported by the Innovative Cluster Creation Project promoted by MEXT and by a grant to RCAST at Doshisha University from MEXT.]

Wireless microphone system, voice receiving apparatus, and wireless microphone

Herein disclosed is a wireless microphone system comprising a plurality of wireless microphones each having a microphone storage area having a unique global identification element stored therein, each of the wireless microphones operative to collect a voice, convert the voice thus collected into an audio signal, and transmit the audio signal and the global identification element; and a voice receiving apparatus for receiving the audio signal and the global identification element from a wireless microphone. The voice receiving apparatus includes a storage section for storing an identification table including a plurality of local identification elements in association with a plurality of global identification elements. The voice receiving apparatus is operative to assign a local identification element to the wireless microphone in accordance with the global identification element with reference to the identification table stored in the storage section, and transmit the local identification element to the wireless microphone, and the wireless microphone is operative to receive the local identification element, store the local identification element in the microphone storage area, and communicate with the voice receiving apparatus with the local identification element thus stored.