Evaluation Criteria
Before the evaluation, it is necessary to understand some musical terms. The term "sound quality" is generally interpreted as the quality of sound. However, in audio technology it contains three aspects: ⑴ the pitch of the sound, that is, the intensity and amplitude of the audio; ⑵ the pitch of the sound, that is, the frequency of the audio or the number of changes per second; ⑶ the timbre of the sound, that is, the audio Overtones or harmonic components. To judge the sound quality of an audio product, it mainly measures whether the above three aspects of the sound reach a certain level: that is, whether the pitch has a certain intensity relative to a certain frequency or frequency band, and whether it is within the required frequency range and at the same volume. , whether the amplitude of each frequency point is uniform, balanced, and full, whether the frequency response curve is straight: whether the pitch of the sound is accurate, faithfully reflecting the original appearance of the sound source frequency or components, and whether the frequency distortion and phase shift meet the requirements; The overtones of the sound are moderate, the harmonics are rich, and the timbre sounds beautiful. There are also some terms:
1. Sound quality: Sound quality is the most basic and extensive evaluation term for evaluating audio equipment.
2. Tone: The sound will be colored like light. The warmer the timbre, the softer the sound will be, and the colder the timbre, the harder the sound will be. The timbre can be described with words such as "beautiful" and "noble".
3. Sound field sense: This includes the shape, front and rear position, height, width, depth and other items of the sound field.
4. Sense of layering: This is the clarity of sound produced by the rows of instruments from front to back in the sound field, as well as the clarity of the intervals between instruments.
5. Positioning sense: To put it simply, the point where the sound of human voice or musical instrument occurs is clear and the position is accurate. Generally speaking, a floating voice means a poor sense of positioning.
6. Transparency: The best sense of transparency and the sound that is not harsh are the most durable. Each pair of human ears has different levels of listening resistance and intolerance. Therefore, there are different standards for the quality of transparency.
7. Imaging power and physical sense: As the name suggests, strong imaging power is the ability to condense ethereal audio and video into entities. In other words, it is the ability to express the physical form of human voices or musical instruments. When the imaging power is good, you can clearly feel the three-dimensional effect of the audio and video.
8. Analytical power: Subtle changes in music can be clearly expressed.
9. Overall balance: mainly refers to the appropriate volume distribution of high, medium and low frequency bands. Reasonable high, medium and low volume is the overall balance. When listening to music, you will feel that the music is soft but powerful, bright, cheerful and layered, clear, integrated and three-dimensional, with a strong sense of presence.
Evaluation Tools
If you want to do your job well, you must first sharpen your tools. First of all, you must choose the most important tool in the evaluation process - earplugs or headphones (in the following article, all earplugs or headphones, etc., are collectively referred to as headphones). Good headphones can directly reflect the quality of MP3 sound. Speaking of headphones, I can’t help but want to complain. Because during long-term observation, the author discovered some sad phenomena: at least 70% of MP3 Walkman users have been using original headphones. As for these original headphones, the sound quality is basically not worth mentioning. Even the Deepsea Serre MX300 and the like, the quality is not much better. No matter how good the MP3 is, it is useless. Does this phenomenon indicate that our national music appreciation ability is declining? Or are you ignoring the expressive power of music? The author suggests that when buying an MP3 player, you should also consider choosing a pair of excellent headphones, so that you can get better sound effects when paired with MP3. The author usually uses many headphones for auditions, including SONY MDR-E888, SONY MDR-E575, SONY MDR-E565, AIWA HP-X705, AIWA V743, STAR 001A, etc., but the most commonly used ones are the delicate MDR-E888, High resolution 001A and balanced X705.
After preparing the headphones, you need to consider what music to use for testing. Take out a familiar CD and use EAC and LAME to convert the music on the disc into a 320KBPS MP3 format file, or use MEDIAPLAYER 9 to convert it into a 192KBPS WMA format file. It is recommended to use a 320KBPS MP3 format file, both theoretically and In practice, MP3 encoding format is better than WMA. In terms of CD audition discs, it is required to find music with better recording technology, a wide sound range, or music with superior performance in a certain frequency band. The author recommends using "HIFI Four Seasons", "The First Drum of Yanhuang", Tsai Chin's "Folk Song" or other famous brand audition discs such as Swansea, Sound of Berlin, etc.
According to the basic principles of evaluation, it is very difficult to judge the pros and cons of a certain product without comparison, just like evaluating the sound quality of MP3. Unless you have accumulated rich listening experience, you already have standards for judging the quality of sound in your mind. Therefore, when evaluating, it is best to prepare a machine with better sound quality than the MP3 to be evaluated, such as a CD player, for direct comparison with the MP3, so that the two can be clearly compared in different types of music. difference.
After the author lost the SONY EJ01, he could only use the SONY SJ01 and PANASONIC CT570, two CD players with relatively good sound quality, as reference for evaluation.
Evaluation method
When the preparations and evaluation tools are ready, you can start testing the MP3 sound quality. But how exactly does it work? For novices, you can first select a certain song and listen to it carefully and repeatedly in the CD player until you think you are more familiar with the various frequency bands and detailed performance, then use the same pair of headphones to listen to the song played on MP3 Effect. While listening, analyze the difference between the sound from MP3 and the sound from CD player. What are the differences? For example, the bass, which of the two is thicker and more powerful; the treble, which is clearer or hazy. What's the difference in mid-range vocals. Generally speaking, bass is the easiest to distinguish, followed by treble, then mid-frequency and details in each frequency band; there are also performances such as field sense, timbre, etc.
After trying out a song, you should have a certain impression in your mind. At this time, you can use the above method to listen to other songs. After trying them out, I already have a clear impression of the sound quality performance of CD players and MP3 players, and I can roughly tell the pros and cons. You can also try using different headphones for evaluation, maybe you will get a different view. If you want to evaluate MP3 sound quality more skillfully, you have to listen to, think about, and compare various types of music more.
The sound quality evaluation mentioned above is completely subjective, because everyone’s hearing and listening habits are different. Therefore, only subjective evaluation cannot meet the evaluation standards. There must be objective Or direct data performance can determine the quality of its sound quality. However, making an objective evaluation is not as casual as a subjective evaluation. In addition to sophisticated equipment and a powerful computer system, it also requires considerable professional knowledge. It cannot be done casually. The author used an extremely objective test method when doing MP3 horizontal evaluation before. The main idea is to use MP3 to play a flat frequency of 15-20KHZ, and then through equipment processing, finally collect the frequency curve during playback on the computer to obtain an intuitive frequency performance chart. This chart can directly reflect the ability of MP3 to restore frequencies during playback, so that it can directly judge the quality of its sound.
Only when subjectivity and objectivity are combined can the sound quality of audio products be correctly judged. Due to limited conditions, we can only work more on the subjective aspect.
Summary
Many consumers believe that cheap MP3 will not have good sound quality. The higher the price, the better the sound quality will be. In fact, this is not the case. It does not mean that cheap MP3 players do not have good sound quality. The author has also tried and encountered many low-cost MP3 products with superior sound quality. Therefore, in the process of sound quality evaluation, we must first eliminate such an erroneous logic. Every sound quality evaluation is a learning process. Perhaps you can discover new things in music during every evaluation process. During the evaluation process, you can also improve your ability to appreciate various music and continuously discover rich musical connotations.