- Jan 19, 2018 -
How do you measure the good and bad of a headset from those aspects?
The earphone can be used to evaluate speakers, but the earphone's listening is different from that of speakers. The sound emitted by speakers can be attenuated and interfered in the air, interacting with human head and ears, and the earphone's voice is directly into the ear.
Headset sound quality is more important than its technical performance, the head and the shape of the ear is different, a headset has a different sense of listening to different people, so it is recommended only as a reference, we must have the opportunity to personally listen to can really feel the headset sound.
What is a high fidelity headset? The main performance of high fidelity headset recommended by the International Electrotechnical Commission IEC581-10 file is: the frequency range of not less than 50Hz-12500Hz, the best response frequency is about 5-45000Hz dynamic headset; typical frequency response of the allowable error of plus or minus 3dB; the frequency response curve of the slope is less than 9dB per octave; unit in the same octave bandwidth in the average sound pressure level the difference is not more than 2dB in 250Hz-800Hz; the range of 100Hz-5000Hz, the sound pressure level is 94dB, the harmonic distortion is less than 1%, 100dB less than 3%; the biggest advantage relative to the speaker of the headset in detail, the actual listening to a good headset should be detailed, clear voice, without audible distortion; low frequency dive and clear, effective control of the entire band; to smooth smooth, high frequency but bright or too dark. For any a headset, the triple could not have been perfect, smooth and natural connection between them is the most important.
The comfort of the headset is also very important, such as using a headset and other activities are to be taken into account, a headset can not be too tight or too loose, should be worn for a long time. The adjustability of the headband and unit can guarantee the use of different head shapes and different uses. Professional audio persons sometimes need single cell monitoring, and units need to be rotated. The length of the other lines and the way of incoming lines are also factors that affect the use. Pay attention to adjust the headband length: headband short, the head of the pressure head, ear pressure on small, with long instead is the most comfortable three point pressure balance for the adaptive with this problem did not exist. There are some ear headset with Pentagon design, can be more fitting ear, more comfortable to wear.
Durability is very important in the field of portable audio, portable audio headset is small and light, easy to be damaged; professional headset and mobile line frequently, also easy to be crushed and broken, the requirements of the headset manufacturing is very strong, and easy maintenance and replacement parts.
Another one related to durability is to bear the power. A small power can push the earphone very loudly. If it exceeds the power, it will damage the earphone. The power of the general civil earphone is less than 100mW, and the professional headset is 100mW-1000mW. High impedance headphones have strong resistance to sound circles and are not as sensitive to power changes as low impedance headphones, and more durable.
The technical parameters of the headset are very important, but it may be misleading. The sound quality of the beautiful headset is not good and the sound of the flat headset may not be bad.
The headset is the impedance of AC impedance, which is the size of coil DC resistance and the inductance of the coil and the Z= (R2+ 2L2 1/2).
The impedance of the earphone and the professional earphone is generally less than 100 ohms, and some professional headphones are more than 200 ohms. This is to reduce the load of the amplifier when a power amplifier pushes more than one earphone. Headphones with high driving impedance need more power. The relative impedance of the earphone is low, and even the flagship earphones like the Tianlong D7100 are only 25 Europe and are very easy to drive.
Sensitivity usually said headset is actually the headset sensitivity level, it is applied electric power to the headset 1mW, the headset is coupled to the artificial ear (fake head) the sound pressure level of 1mW in power frequency 1000Hz standard headset impedance is calculated on the basis of the. The unit of sensitivity is dB/mW, and the other is dB/Vrms, the sound pressure level produced when the 1Vrms voltage is applied to the headset. The sensitivity is high, which means that the power required to achieve a certain sound pressure level is very small. The sensitivity of moving coil earphone is usually above 90dB/mW. If the headphones are selected for the Walkman, the sensitivity is best at 100dB/mW or higher.
The sensitivity of speakers is the sound pressure level generated at the input of 1W power at 1 meters. For earphone and speakers with similar sensitivity, the power required for earphone is equivalent to the 1/1000 of speakers. In fact, this value is even smaller, because few people listen to speakers at the distance of 1 meters.
The distortion of earphone is usually very small. The total harmonic distortion (THD) of the earphone is less than or equal to 1% at the maximum power, which is basically not audible, much smaller than that of the loudspeaker.
Sensitivity has different values at different frequencies, that is, frequency response. The dependence of sensitivity on frequency is expressed in curves, which is called frequency response curve. The range of human hearing is 20Hz-20000Hz. The voice beyond this range can not be heard by most people. The frequency band of earphone can be replayed quite wide, and the excellent earphone has been able to reach 5Hz-45000Hz. The frequency response of general earphone is positive or negative, 10dB. The frequency response of professional earphone and some high-end earphones is positive or negative 3dB, which causes a lot of low-frequency headphones with frequent frequency response, and the frequency of high-grade headphones is even. A frequency response curve of the real straight headset it sounds not good, because before entering the ear in the head and the sound has produced the peaks and valleys, so often a balanced way in headset design, make the ears of the received frequency response curve is relatively flat.
Diffusion field equilibrium
There are two ways to balance headphones: the free field equilibrium and the diffusion field equilibrium; the free field equilibrium assumes that the environment is not reflected, such as the wilderness; the diffusion field equilibrium simulates a reflecting room, and its hearing sense is more natural than the free field equilibrium. The IEC's method of testing the flatness of the diffusion field is seen in the standard IEC60268-7. But the diffusion field equilibrium is based on the standard head shape and room model. It will not satisfy all users, nor is it suitable for some recording, such as fake head recording.