Making transducers sound as natural as possible is quite a challenge for audio tuners. While subjective evaluations help designers fine-tune sound, they face several challenges, such as visual cues impacting both audio perception and quality.
Objective measurements help mitigate some of the challenges posed by subjective evaluation. Objective evaluations also help when making A/B comparisons. When conducting objective or subjective tests, audio tuners prefer high-quality audio recordings over highly compressed MP3/AAC files. Raw WAV files are the best.
To perform objective analyses, you need a good-quality microphone; an audio sound card to capture the microphone data to your PC; and software tools like MATLAB, Audacity and Room EQ Wizard (REW).
Figure 1 depicts an experimental setup using the TAS2555 audio amplifier, a TI SmartAmp.
Figure 1: Typical lab setup for audio measurements
These are some of the objective parameters that can help audio tuners judge the perception of audio loudness and quality.
LoudnessOne of the main objectives of TI’s TAS2555 is to drive the speaker to its maximum limits while protecting it against electrical or mechanical failures. The peak and average sound pressure level (SPL) measurements help determine this objectively.
I use REW for an analysis like the one shown in Figure 2, which also uses the TAS2555 audio amplifier to analyze a popular rock song.
Figure 2: SPL measurements
TimbreIt is imperative that while your solution should sound as loud as possible, it should not be at the expense of audio quality/timbre.
Table 1: Mapping subjective experiences to objective parameters
The subjective analysis is objectively possible by studying the tracks (the input being the raw file/audio captured from the reference system vs. the output being speaker audio captured via mic) with these parameters:
I used the TAS2555 as my example because it can use PurePath™ Console software, which helps you tune the solution to meet your signature sound. PurePath™ Console software is an easy-to-use audio-development suite that helps you evaluate, configure and debug audio products during development. Access to PurePath™ Console software enables you to identify issues and ensure the best possible sound.
TAS2555 vs. coventional solutionTable 2 shows the average values of timbre parameters for measurement across 18 different tracks from various music genres (blues, rock, classical).
Table 2 - Comparison of objective parameters between TAS2555 and a popular phone
Tuning an audio solution to get the most natural sound possible is often hard and takes a lot of time. There are several tools out there to help with this process; however, it is important to make sure that you account for (and correct if needed) the elements of sound that I’ve covered in this post. If you have had similar problems in the past, please leave a comment below. How do you fine-tune your sound?
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