# Dynamic Range Compression and the Semantic Descriptor Aggressive
## 1 Introduction
### Background
The results showed that there was a non-linear relationship between the octave bands and changes to the crest factor. Of interest to professionals is the result which shows that modifications to the crest factor in a band centered around \(125\) Hz does not correlate with perceived loudness at moderate playback levels. Moreover, the perceived loudness could be louder than one might expect. The authors recommended that music engineers should be cautious of compression activities that affect the low end. Some noteworthy work was conducted by [PERSON] et al. [15] which sits outside of the hyper compression studies reviewed so far. The authors of this paper investigated the lexicon of words used to describe analogue compression. [PERSON] et al. conducted a discourse analysis on \(51\) reviews of analogue mastering compressors to look for common terms used in the texts and created inductive categories to group the words. The categories they created included signal distortion, transient shaping, special dimensions and glue. A qualitative investigation of a similar nature was carried out for the current study, and the results are presented in Chapter 3. Interestingly, a number of the descriptors gathered by both studies are similar, but aggressive was not included in the work by [PERSON] et al., suggesting that this descriptor is not commonly used to describe the sound of mastering compression. Other connected work has been carried out by scholars involved with the Semantic Audio Labs and the Semantic Audio Feature Extraction (SAFE) project. SAFE aims to understand the audio features associated with semantic descriptors, which can then be used to create intelligent mixing tools. [PERSON] et al. [16], investigated terms used to describe signal processing on the mix and conducted hierarchical clustering to look for similarities in the terms. The authors presented dendrograms relating to the signal processing techniques, compression, distortion, equalization and reverb. The word aggressive was not included in any dendrogram and, surprisingly, not in the distortion group. The authors do not stipulate which sources the signal processing techniques were applied to. So, the influence of source on the descriptor is not apparent, which is important to consider and will have played a role in the results. Hence, the current study focuses solely on vocal compression. [PERSON] et al. [17] looked into compression ballistics (attack and release settings) and how they affected the perception of music mixes in four styles: Rock, Jazz, HipHop and Electronic Dance Music. They asked participants to rate which ballistic setting was the most appropriate for a genre and to select from a list of given words to describe the sound quality of their preferred setting. They discovered that attack played a more significant role on appropriateness than release, with the result applying most strongly to Jazz and Rock. It should be noted that this study made use of a Solid State Logic (SSL) bus compression emulation, which has a much slower attack time than the 1176 compressor used in the current study. Not directly related to compression, but in the domain of semantic music production, is the work by [PERSON] and [PERSON] [18], which aims to develop a perceptual model to measure \"punch\" in music productions. As noted by [PERSON] and [PERSON], punch is an attribute that is used by music listeners to describe a sense of power and weight in audio material. Their work uncovered that punch is related to \"a short period of significant change in power in a piece of music or performance\" as well as dynamic changes to particular frequency bands in the program material. The authors of the work went on to develop a perceptual model of punch for use in a real-time punch meter. The author of the current study advocates the creation of similar meters to measure other perceptual attributes, such as the one in this study, which can be integrated into modern digital audio workstations (DAWS) for use in music production activities.