Since noise-induced hearing loss (NIHL) is one of prevalent issues in the occupational settings, hearing protection device (HPD) has been widely used to reduce noise exposure levels and to prevent developing NIHL. This review study aimed to introduce several types of the HPD in terms of current trends, its variety and functions, and application. Including a brief history of the HPD, we explain its two types, i.e., passive and active functions, in the first part of main body. The passive HPD has a flat attenuation across the overall frequency range, whereas the active HPD effectively preserves communication components such as meaningful speech with low intensity stimuli while filtering out the high levels of noise. In the second part of the main body, we discuss some negative issues of hearing functions when users are wearing the HPD. In detail, the active HPD does not much degrade the hearing performance for speech detection/recognition and sound source localization compared to the passive HPD. Rather, reduced sound (or music) quality is improved with active one in general. In the final part, we mention that although various applications in the special fields such as factory, mining, army, airplane, and music have been demonstrated, the usage and awareness of HPD in occupational aspect may not follow its fast technological development. Furthermore, most people do not know about either importance or use method of HPD in the non-occupational setting. For these reasons, we conclude that hearing professionals have to access the latest trends of the HPD and to increase their knowledge on it, and thus they should provide the best HPD prescription for the public as well as employees who have to protect their ears from hazard noise impacts.

Background and ObjectivesClear speech is an effective communication strategy used in difficult listening situations that draws on techniques such as accurate articulation, a slow speech rate, and the inclusion of pauses. Although too slow speech and improperly amplified spectral information can deteriorate overall speech intelligibility, certain amplitude of increments of the mid-frequency bands (1 to 3 dB) and around 50% slower speech rates of clear speech, when compared to those in conversational speech, were reported as factors that can improve speech intelligibility positively. The purpose of this study was to identify whether amplitude increments of mid-frequency areas and slower speech rates were evident in Korean clear speech as they were in English clear speech.Subjects and MethodsTo compare the acoustic characteristics of the two methods of speech production, the voices of 60 participants were recorded during conversational speech and then again during clear speech using a standardized sentence material.ResultsThe speech rate and longterm average speech spectrum (LTASS) were analyzed and compared. Speech rates for clear speech were slower than those for conversational speech. Increased amplitudes in the mid-frequency bands were evident for the LTASS of clear speech.ConclusionsThe observed differences in the acoustic characteristics between the two types of speech production suggest that Korean clear speech can be an effective communication strategy to improve speech intelligibility.

Background Sound therapy is generally considered as an effective method for relieving tinnitus. There have been various reports on the effects of tinnitus interventions involving sound therapy as a component; however, there have been only a small number of reports on the effects of sound therapy itself on tinnitus. Purpose The aim of the study is to elucidate whether sound therapy significantly improves tinnitus as determined by subjective measurements. Research Design Prospective study involves within-subject (baseline, 3-month, 6-month) measurements. Study Sample This includes 16 adults with subjective and sensorineural tinnitus. Intervention Participants undertook sound therapy for 3 hours a day for 6 months. The level of stimulus for sound therapy was set to the mixing point of each participant. No counseling was provided. Data Collection and Analysis Participants rated the visual analog scale for loudness and annoyance using a numeric 0 to 100 point scale and completed the Korean version of the Tinnitus Primary Function Questionnaire at the baseline, 3-month, and 6-month time points. Results Sound therapy led to significant improvements of tinnitus in participants in all subjective measurements. Significant effects were found not only between the baseline and 3-month but also between the 3-month and 6-month follow-ups. Conclusion Results of the present study showed that the sound therapy alone led to significant improvements of tinnitus in participants as assessed by subjective measurements. To improve the effects of sound therapy, consistent sound therapy may be required for a certain period of time such as 3 hours a day over a 6-month period.

Sound therapy is known to be a useful treatment option for tinnitus rehabilitation. The purpose of this paper was to review sound therapies that reported effects of tinnitus masking or tinnitus relief. Four sound therapies were reviewed: masking sound therapy, sequential sound therapy, sound therapy for Tinnitus Retraining Therapy, and notched sound therapy. Each sound therapy was reviewed for purpose of the therapy and definition, protocol of the sound therapy, effects of tinnitus relief or masking, usefulness, and limitations. Many researchers have investigated sound therapies using above mixing point sounds, at or below the mixing point sounds, and notched sounds. Most researchers reported that sound therapy is effective on tinnitus, but there is inconsistency regarding the extent of the masking or relief effects. Few researchers reported a sound therapy using sequential sounds. Although some studies have shown efficacy for these sound therapies, further studies are required for more reliable results. Although various sound therapies have identified positive effects of tinnitus relief or masking, information about selecting the appropriate rehabilitation method for each tinnitus sufferer is insufficient. However, the results of this paper will provide a basic guideline for audiologists or clinicians selecting a sound therapy for people who have tinnitus.

For decades, tinnitus questionnaires have used as an effective tool to evaluate the degree of tinnitus relief or a patient's subjective perception of tinnitus. The purpose of this study was to review four tinnitus questionnaires that have primarily been used in clinics. The Tinnitus Handicap Questionnaire (THQ), Tinnitus Handicap Index (THI), Tinnitus Functional Index (TFI), and Tinnitus Primary Functional Questionnaire (TPFQ) were reviewed for development background, purpose of development, developmental process, questionnaire characteristics, reliability test results, and pros and cons of each questionnaire. Each tinnitus questionnaire has their own characteristics in terms of evaluations and interpretations. Especially, the THQ is focused on social, emotional, and physical impacts and the THI is focused on catastrophic loss of life, functional, and emotional factors. The TFI is mainly focused on quality of life, cognitive, and emotional factors. The TPFQ is focused on hearing, sleep, concentration, and emotional factors. The current study provides detailed information about four questionnaires. If each questionnaire is correctly identified and applied, effective measures of tinnitus and the degree of tinnitus relief through rehabilitation can be efficiently measured.