直昇機噪音之頻率分析(1Hz~4kHz)

Study on Frequency Analysis from 1 to 4,000 Hz for Helicopter's Noise

10.30017/EP.200206.0003

郭宏亮(Hung-Lian Kuo)；盧天鴻(Tien-Hung Lu)；王世傑(Shin-Chieh Wang)

直昇機噪音 ； 頻率分析 ； Helicopter's noise ； Frequency analysis

環境保護

25卷1期（2002 / 06 / 01）

24 - 30

繁體中文

直昇機不同於一般航空器，因其推進之機能、使用的目的及無固定之航道，經常低空盤旋於住宅區之上空，其所產生之噪音對環境之影響是不可忽視的。本文針對目前在台灣使用中軍用不同機種之直昇機所產生的噪音，做了1Hz至4kHz之1/3音階之頻率分析，從量得之頻率分析圖瞭解直昇機噪音的特性，其結果如下： 1.直昇機噪音在頻率250Hz以下的音量較大，而頻率超過250Hz時，其音量有明顯下降之趨勢。 2.大體而言，大部份低頻噪音都分佈在10~40Hz之間。 3.在同一高度降落之噪音比起飛噪音大。 由以上得知，直昇機所產生的噪音大都偏向低頻的範圍，且與飛行速率及高度有關。當其經過住宅區之上空時，所產生之噪音對環境之影響程度，尚無適當之法條來規範，唯有修改目前之管制標準方能有效地管制直昇機所產生的噪音。其次，在防音技術及防音材料方面也應考慮對低頻部份之防音研究。

Helicopter uses rotating blades as power for landing, take-off, and propelling, so the created noise may include low-frequency, which is not the same as other kinds of aircraft. Furthermore, when the helicopter flies in the sky, it has no fixed air route and often whirls above the residential area with low-altitude for some particular purposes, the residents been affected by this kind of noise can not be neglected. The 1/3-octave-band spectra with center frequencies from 1 to 4,000Hz obtained from different kinds of helicopter are analyzed in this study. From the analytical diagrams, the characteristic of the helicopter's noise will be known as follows: 1. The values of the noise level are large while the center frequencies under 250Hz; but if the center frequencies are over 250Hz, the values of the noise level tend to decrease evidently. 2. In general, the frequency range of the helicopter's noise distribute from 10 to 40 Hz which belong to the so called low-frequency. 3. At the same flying altitude, the values of noise level are higher while the helicopter lands than that it takes off. As mention above, the frequency distribution of the helicopter's noise tends to low-frequency range, and its value of noise level is relevant to the cruising speed and flying altitude of the helicopter. At present, there is no ordinance to rule the helicopter's noise impacting the environment while it whirls above the residential area. It shall have to revise the present ”Noise Control Laws” to prevent the environmental impact due to the helicopter's noise. To improve the sound absorption materials for the low-frequency noise is also an important study in the future.