Jansson Karl-Johan Fredén, Håkansson Bo, Johannsen Leif, Tengstrand Tomas
* Department of Signals and Systems, Chalmers University of Technology , Göteborg , Sweden.
Int J Audiol. 2015 May;54(5):334-40. doi: 10.3109/14992027.2014.980521. Epub 2014 Dec 18.
The objective is to evaluate the electro-acoustic performance of a new audiometric bone vibrator, the B81 from Radioear Corporation, USA. Comparison will be made with the widely used B71 which has well-known limitations at low frequencies.
The B81 is based on the balanced electromagnetic separation transducer (BEST) principle where static forces are counterbalanced so that nonlinear distortion forces are reduced and maximum hearing levels can be increased.
Maximum hearing level, total harmonic distortion (THD), frequency response, and electrical impedance were measured for six devices of each bone vibrator type on an artificial mastoid.
It was found that B81 reaches 10.7-22.0 dB higher maximum (@ THD = 6% or Vin = 6 VRMS) hearing levels than B71 for frequencies below 1500 Hz, and had significantly lower THD up to 1000 Hz. There was no statistically significant difference between their frequency response, except a deviation at the mid frequencies (α = 0.01) where B81 was more efficient and the electrical impedances were practically the same.
In general, B81 had an improved electro-acoustic performance compared to B71 and is compatible with same audiometers. In particular, B81 allows for sensorineural hearing loss to be measured at considerably higher hearing levels than with B71 below 1500 Hz.
评估一款新型听力计骨导振子——美国Radioear公司的B81的电声性能。将其与广泛使用但在低频存在众所周知局限性的B71进行比较。
B81基于平衡电磁分离换能器（BEST）原理，即静电力相互抵消，从而降低非线性失真力并提高最大听力水平。
在人工乳突上对每种骨导振子类型的六个设备测量最大听力水平、总谐波失真（THD）、频率响应和电阻抗。
发现在1500Hz以下频率，B81的最大听力水平（@THD = 6%或Vin = 6 VRMS）比B71高10.7 - 22.0dB，并且在高达1000Hz时THD显著更低。除了在中频处有偏差（α = 0.01），B81在中频处效率更高且电阻抗基本相同外，它们的频率响应没有统计学显著差异。
总体而言，与B71相比，B81的电声性能有所改善，并且与相同的听力计兼容。特别是，在1500Hz以下，B81能够在比B71高得多的听力水平下测量感音神经性听力损失。
