The significance of masking for the poor hearing ear in pure tone audiometry

Abstract

Background

In pure tone audiometry, when the difference of the Average Air Conduction Threshold of pure tone (AACT) between bilateral ears is more than 40 dB HL masking must be performed on the poor side, However, we found that masking also make significance difference when the binaural AACT difference (AACT-d)was less than 40 dB HL in some patients.

Aims/Objective

Assessing the significance of masking for the poor ear in pure tone audiometry in patients with different types of deafness to obtain preoperative accurate hearing.

Material and methods

A comparative analysis of 163 cases (163 ears) with hearing difference between two ears was conducted, who were divided into three groups: G1 Congenital Malformation of the Middle and Outer Ear (CMMOE)as conductive deafness, 63 ears, G2 sudden deafness as sensorineural deafness, 65 ears, and G3 media otitis as conductive or mixed deafness,35 ears. AACT-d before and after the poor ear masking was analyzed under the following three conditions: (1) 0.125–8 KHz each frequency, (2) 0.5–4 KHz on average, (3) the frequencies of AACT-d ≥ 40 dB HL and <40 dB HL between the two ears before masking. If the sample data did not follow a normal distribution, the Wilcoxon rank sum test was used for comparasion of AACT, and p < 0.05 was considered statistically significant. It is clinically effective for AACT-d ≥ 15 dB HL at 1 frequency or 10 dB HL ≤ AACT-d at 2 frequencies <15 dB HL before and after masking.

Results

Among the three groups, (1) the comparasion of AACT-d before and after the poor ear masking for each frequency of 0.125–8 KHz and 0.5–4 KHz on average with all p < 0.05, and the AACT-d of the G1 group was the largest, with an average 0.5–4KHz of 7.5 dB HL, and the first two were 14.5 dB HL and 13.8 dB HL at 0.125 KHz and 0.25 KHz, respectively. (2) AACT-d ≥ 40 dB HL and <40 dB HL between the two ears before masking were distributed at the full frequency of 0.125–8KHz, the clinically effective rates of ≥40 dB HL groups were G1 (89.3%), G2 (45.5%) and G3 (5.3%), while those of < 40 dB HL groups were G1 (69.7%), G2 (34.4%) and G3 (31.3%), respectively.

Conclusion and significance

For all three groups, there was statistically significant in AACT-d before and after the poor ear masking across each frequency of 0.125–8 KHz and on average 0.5–4 KHz. The distribution of AACT-d ≥ 40 dB HL and <40 dB HL between the two ears before masking was observed throughout the full frequency range of 0.125–8 KHz. AACT-d before and after the poor ear masking showed clinical effectiveness in all three groups, with the highest effective rate observed in the G1 group and the highest AACT-d at 0.125 KHz and 0.25 KHz. Therefore, regardless of whether the AACT-d between the two ears before masking is ≥40 dB HL or <40 dB HL, the full frequency masking should be employed in three groups, especially for the G1 group of CMMOE, particularly at 0.125 KHz and 0.25 KHz.

Chinese Abstract

背景: 纯音测听时, 当双耳之间纯音平均气导阈值(AACT)的差异大于40dB HL时, 必须对不良侧进行屏蔽。但是, 我们发现, 有些患者双耳AACT差异 (AACT-d) 小于 40dB HL时, 屏蔽也会产生显著差异。

目的: 评估屏蔽对于不同类型耳聋患者纯音听力测试中的不良耳朵的重要性, 以获得术前准确听力值。

材料与方法: 对163例(163耳)两耳听力差异的患者进行比较分析, 并将其分为三组: G1, 先天性中耳和外耳畸形(CMMOE), 为传导性耳聋, 共63 耳；G2, 突发性耳聋, 为感音神经性耳聋, 共65 耳；G3, 中耳炎, 为传导性或混合性耳聋, 共35 耳。对不良耳进行屏蔽之前和之后的AACT-d在以下三种条件下进行分析: (1)每个频率0.125-8KHz；(2) 平均0.5-4KHz；(3) 屏蔽之前两耳间AACT-d ≥ 40dB HL和<40dB HL的频率。 如果样本数据不呈正态分布, 则 Wilcoxon 秩和检验用于比较 AACT, p<.05 被认为具有统计学意义。1 个频率下 AACT-d ≥ 15dB HL 或 2 个频率下 10dB HL ≤ AACT-d, 屏蔽之前和之后<15dB HL, 这在临床上确实有效。

结果: 三组中, (1)不良耳屏蔽前后AACT-d的比较对于 0.125-8KHz 的每个频率和 平均0.5–4KHz 的每个频率, 所有的 p<.05, G1 组的 AACT-d最大, 7.5dB HL的平均0.5-4KHz, 前两组在0.125KHz 和 0.25KHz 处分别为14.5dB HL 和13.8dB HL。 (2) AACT-d ≥ 40dB HL 和 <40dB HL 组之间屏蔽前两耳分布于0.125-8KHz全频, 临床有效≥40dB HL组的发生率分别为G1(89.3%)、G2(45.5%)和G3(5.3%), 而<40dB HL组的发生率分别为G1(69.7%)、G2(34.4%)和G3(31.3%)。

结论和意义: 对于所有三组, 0.125-8KHz 的每个频率和平均 0.5-4KHz 的不良耳屏蔽之前和之后的AACT-d均具有统计学意义。 观察到屏蔽前两耳间AACT-d ≥ 40dB HL和<40dB HL在 0.125–8KHz 的整个频率范围内的分布。不良耳屏蔽前后的AACT-d显示所有三组均显示出临床有效性, 其中 G1 组有效率最高, AACT-d 在 0.125KHz 和 0.25KHz频率处最高。因此, 无论屏蔽前两耳间的AACT-d 是否≥40dB HL或<40dB HL, 三组都应使用全频屏蔽, 特别是CMMOE的G1组, 尤其是在0.125KHz和0.25KHz频率处。

Keywords:

• Pure tone audiometry
• masking
• Congenital Malformation of the Middle and Outer Ear (CMMOE)
• sudden deafness
• otitis media

Disclosure statement

No potential conflict of interest was reported by the authors.

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by the National Clinical Medical Center Special Project: YiHui Zou (202100003) and National Logistics Support Department Special Family Planning Project: YiHui Zou (22JSZ14).