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1
Content available remote

Subjective Evaluation of Directional Properties of Loudspeaker Systems with the Analog and Digital Crossover Networks

100%
Niewiarowicz M., Galiński T.
Acta Physica Polonica A
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2013
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vol. 123
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issue 6
974-979
EN
The aim of this study was to determine the way in which loudspeaker systems with the analog and digital crossover networks were subjectively evaluated. The object of the study were two loudspeaker systems, differing in both the position of speakers on the front panel of enclosure and configuration of the crossover networks: 2.5-way and 3-way systems with the slope of frequency response of 12 dB/octave in the cut-off regions. The investigations were conducted for 5 angles from the front hemisphere in the horizontal plane. Test signals were fragments of music and speech. The recordings of these signals were conducted in an anechoic chamber using an artificial head and then presented to the listeners through headphones. Five normally-hearing listeners aged 18-50 years took part in the experiment. Listening tests were carried out in two stages. In the first stage listeners were listening to test signals grouped in triads and their task was to identify pairs of signals the most and the least similar to each other. In the second stage a parametric evaluation was performed. It consisted in assigning five numbers, corresponding to the intensity of the attribute of perception space (evaluated on a scale of 0-10) to each of test signals. The attributes of perception space included: sharpness, clearness, fullness, lack of distortions and loudness. Using the method of multidimensional scaling and correlation analysis it was possible to relate a particular dimension of the multidimensional space to the attributes of the perception space. It was found that the intrinsic attributes responsible for the subjective evaluation of loudspeaker systems with the analog and digital crossover network were sharpness, clearness and loudness.
2
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Spatial Impulse Response Assessment in Room Acoustics Auralization

80%
Małecki P.
Acta Physica Polonica A
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2015
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vol. 128
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issue 1A
A-17-A-21
EN
Ambisonic impulse responses (also known as the Spatial Impulse Responses) are getting more and more popular in many applications of room acoustics. Measuring, modeling, synthesizing, or simulating acoustics of interiors with emphasize on their spatial features are the examples. The present article shows a methodology of room acoustics auralization assessment using the ambisonics technology. A case study is shown for room acoustics capturing (measuring the Spatial Impulse Response) and reproducing with the use of a multi-channel sound system. An discussion and considerations about fidelity of such reconstruction is provided. Furthermore, a quantitative measure for the auralization quality is proposed. Also on-site experiments are described and their results presented to illustrate the theoretical considerations and outline options for future work. Obtained results show that most of the proposed quality factors meet the assumptions. After possible future modifications and additional research, the proposed methods could be used in evaluation of room acoustic auralization.
3
Content available remote

Audiologic-Acoustic Evaluation of Speech Perception in Children with Cochlear Implants

80%
Stieler O., Sekula A., Karlik M.
Acta Physica Polonica A
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2011
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vol. 119
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issue 6A
1077-1080
EN
An early diagnosis of the congenital disorder of hearing creates new challenges for a multidisciplinary team: paedoaudiologists, ear nose throat specialists, and speech therapists. The cross modality matching method is based on the objective and subjective techniques in the evaluation of hearing thresholds in children. The electrical response audiometry provides information about the response of the brainstem to acoustic stimulation; the behavioural audiometry gives information about the perception and central associative processes in the auditory pathway. The paediatric fitting procedure relies on solid foundations of behavioural measurement to ensure the validity of hearing aid and cochlear implant fitting. This study assessed perception of phonemes in children with the cochlear implants and possibilities of applying acoustic solutions to the audiologic evaluation. The authors have also examined the possibilities of applying digital audio processing algorithm in clinical practice. Self-developed computer controlled diagnostic stations were used and tested. Speech perception was assessed on the basis of Erber's categories. Detection, discrimination and identification tests of 5 Ling phoneme were used. The sample comprised 23 implanted children, aged 3-6 years, who received a cochlear implant when they were 18 to 30 months old. The detection thresholds, discrimination and identification scores were assessed. Tests based on phonemes aa, uu, ii, ss, and sh (5 sounds of Ling) were used. The results indicated significant correlations between pure tone audiometry results and the thresholds of phoneme detection [dB SPL]. The identification score in this group was 95-100%.
4
Content available remote

Real-Time Spectroscopy of Acoustic Waves or Music as Physical Phenomenon

80%
Zieliński P.
Acta Physica Polonica A
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1996
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vol. 89
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issue 2
265-271
EN
The sounds used in music have discrete spectra consisting of a fundamental frequency and of its integer multiples. This is the reason for an affinity of the sounds for which the ratio of the fundamental frequencies is given by a fraction of small integers. Two possible physical mechanisms for this affinity are discussed: (1) an influence of beats between some partial tones and (2) nonlinear interactions between partial tones. Some facts from the music theory are then explained as resulting from the invariance of the most consonant intervals between affine sounds against variations of the timbre and of the register. An analogy is indicated between the classical cadence and the lock-in effect in incommensurate crystals. The lecture is illustrated with extracts from the J.S. Bach Das Wohltemperierte Klavier, the W.A. Mozart sonata for piano KV 570 and a recitative from the Haendel Messiah.
5
Content available remote

Application of Vibratometry in Evaluation of Frequency Detection and Signal Intensity in Patients with Unilateral Cochlear Implants - Preliminary Results

80%
Sekula A., Pruszewicz A., Stieler O., Gibasiewicz R., Karlik M., Komar D.
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EN
Vibratometry is a unique audiological test used in patients with bilateral profound sensori-neural hearing loss. An acoustic stimulus is presented using the bone conduction. The study comprised 15 patients with bilateral profound hearing loss with unilaterally implanted cochlear implant. Vibration detection thresholds were noted. Measurements were done at the implanted side with speech processor either switched on or switched off, as well as at the contralateral side with speech processor switched on. All the patients have perceived stimulus used for testing. The average detection thresholds of vibration stimulus and average thresholds in bone conduction using tonal stimulus have shown better perception of vibration delivered by bone conduction than tonal stimulus. The average detection threshold of vibration stimulus in the implanted ear showed significantly better results in case of speech processor switched on. Patients perceived high frequency stimuli during vibratometry testing despite of no reaction to tonal stimulation during bone conduction test. Vibration could be a supplementary stimulation in patients with bilateral perceptive profound hearing loss.
6
Content available remote

Fidelity Estimation of Watermarked Audio Signals According to the ITU-R BS.1116-1 Standard

80%
Piotrowski Z., Gajewski P.
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EN
The paper describes the method that enables to measure acoustic fidelity of audio signals degraded with digital watermarks. Fidelity measurements of degraded acoustic signals is suitable for such applications as distinguishing whether the acoustic record is signed with a digital watermark (watermarked) or not as well as evaluation of the degradation degree affecting the host signal. The test of subjective assessment according to the recommendation ITU BS.1116-1 is the standard that served as the basis for implementation of a dedicated application within the Matlab environment and for development of the concept how to make this application available as an IP network service to enable assessment of degraded signal by a wider auditorium.
7
Content available remote

Precise Psychoacoustic Correction Method Based on Calculation of JND Level

80%
Piotrowski Z.
Acta Physica Polonica A
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2009
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vol. 116
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issue 3
375-379
EN
This paper constitutes a proposal of a method of spectral shaping of the watermark signal without adjusting the interception point based directly on psychoacoustics of the human auditory system and the proposed calculation formula. The proposed calculation formula enables correction of watermark signal both as regards its spectrum shape and adjustment of watermark signal to the host's JND.
8
Content available remote

Quietness in the Soundscape of the Białowieża National Park

70%
Wiciak J., Mleczko D., Ozga A., Wszołek G., Wierzbicki J., Piechowicz J., Małecki P.
Acta Physica Polonica A
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2015
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vol. 128
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issue 1A
A-79-A-84
EN
The quietness, defined as the near or complete absence of sound, in the context of the natural environment protection, may be considered a state in which no undesired of foreign sounds occur, and, by analogy to noise, analyzed in two aspects: that pertaining to measurements and the subjective one. The article discusses the lowest levels of sounds recorded at night in the soundscape of the Białowieża Forest. Due to low levels of the examined sounds and the technical problems that occurred while the sounds were being measured and registered, the acoustic examination of the measurement set-up in an anechoic chamber has also been presented. The research is aimed at defining precisely the concept of quietness prevailing in the nature in the subjective aspect by determining both the range of levels and the characteristics of preferred sounds.
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