Research On The Relationship Between Frequency Response Of Headphone And Its Cavity

With the rapid development of science and technology today, a headphone as a portable listening device becomes indispensable in people’s entertainment life. And, along with the improvement of the level of daily life, the expectations and requirements of the headset are gradually increased and new demands of headset studying are put forward.. But due to the limitations of its cavity structure and other aspects of the conditions, headphones have inherent poor abilities in reproducing acoustically. Thus, they always can’t meet the people’s pursuit and enjoyment for the sound quality.At present, the domestic study of headphones more focus on the technical problems such as Bluetooth, WiFi and noise reduction. But the design and improvement of headphones’ structure, especially the cavity structure, both in theory and practice, is lack of rich outgiving materials, so, most headset designers are dependent on their own experience to keep trying. Therefore, the study which is based on the electrically- power- acoustic analogy equivalent circuit, puts the geometric parameters of cavity structure as the research object,.. By using three methods such as theory derivation, simulation and experiment, the relationship between frequency response curve and headphone cavity is probed and analyzed systematically. Theoretical analysis shows that: only the influence of the headset cavity is considered, the volume of the front cavity mainly affects the output sound pressure in the medium-high frequency, and the smaller the volume, the better the output characteristics; The impact of the small rear cavity on the output sound pressure is very small and can be neglected; The volume of the large rear cavity mainly affects the output sound pressure in the lower frequency, and the greater the volume, the better the output. The simulation results indicate that: the change of the headphone front cavity geometry parameters have a deep influence on the frequency response and high-frequency formant; while the change of the headphone rear cavity have a greater impact on the frequency formant than on the frequency response。.In order to verify whether the actual listening results are consistent with the theoretical analysis, subjective listening experiments(sound Comparative Experiment) and objective index analysis(measured frequency response curve) are made, differences of the headphone sound quality between before and after the modification of the same paragraph headset are assessed systematically. The objective measurements show that: the change in volume of the headset large rear cavity and its output changes are proportional to each other, the ratio is about 1:7.5. In other words, if the volume of the large rear cavity is reduced by half, the output sound pressure decreases about 7.5dB. Subjective listening test results conclude that: the change of the headphone large rear cavity volume have a great influence on its frequency response curve. The research not only reveals the relationship between frequency response curve and headphone cavity, which laid a theoretical foundation, but also accelerate the headset design process. It is useful to improve the characteristics of sound pressure frequency response of headphone.