Advanced Acoustic Analysis

Wheeze, howling and buzz noises of machines represent a common problem, especially with gearboxes. Due to these tonal components in the overall sound, the sound quality is reduced significantly.
There are many acoustic analyses, which have especially been developed for the evaluation of these acoustic phenomena. This tutorial will show you how these analyses work and when they can be used best. The following analyses are explained by means of practical noise examples:

• Tone to Noise Ratio
• Tonality DIN 45681
• Specific Prominence Ratio
• Specific Tonality (Hearing Model)

A proper analysis is key when comparing different noises to analyze which one is louder. But what is the best analysis for this acoustic test application?
In this tutorial we introduce two different analyses: Sound pressure level [ dB(A) ] and Loudness [ sone ]
We compare the performance with respect to the following aspects:

• Scaling
• Frequency Weighting (A B C D)
• Time Response
• Masking Effect
• Frequency Resolution
• Level of detail
• Time Resolution

FFT analysis is often used for the acoustic analysis of airborne sound or vibrations. However, this method has a conflict between high frequency resolution and high time resolution. In this tutorial we present a real alternative to the classical FFT, which offers much more precise insights than an FFT can provide.

The HSA (High Resolution Spectral Analysis) was invented and developed by HEAD acoustics. HSA is included in the ASM16 module of the analysis software Artemis SUITE, which offers many more high-performance analyses.

Devices and machines require good sound. Sound pressure levels and third octave bands only convey the sound energy - but not the sound quality. Special psychoacoustic analyses such as roughness analysis can be used to analyze disturbing frequencies in the noise spectrum and specifically optimize the sound design.

In this tutorial, we will introduce roughness analysis using two sample data - two closely spaced sine tones and a real aircraft with strong turbine noise. Using the roughness analysis and the sound engineering tool the noise can be detected and analyzed in depth with just a few clicks.