processing. Many audio compression codecs such as MP3 and Opus use a psychoacoustic model to increase compression ratios. The success of conventional audio systems for the reproduction of music in theatres and homes can be attributed to psychoacoustics and psychoacoustic considerations gave rise to novel audio systems, such as psychoacoustic sound field synthesis. Furthermore, scientists have experimented with limited success in creating new acoustic weapons, which emit frequencies that may impair, harm, or kill. Psychoacoustics are also leveraged in sonification to make multiple independent data dimensions audible and easily interpretable. This enables auditory guidance without the need for spatial audio and in sonification computer games and other applications, such as drone flying and image-guided surgery. It is also applied today within music, where musicians and artists continue to create new auditory experiences by masking unwanted frequencies of instruments, causing other frequencies to be enhanced. Yet another application is in the design of small or lower-quality loudspeakers, which can use the phenomenon of missing fundamentals to give the effect of bass notes at lower frequencies than the loudspeakers are physically able to produce (see references). Automobile manufacturers engineer their engines and even doors to have a certain sound. See also Related fields Cognitive neuroscience of music Music psychology Psychoacoustic topics A-weighting, a commonly used perceptual loudness transfer function ABX test Auditory illusions Auditory scene analysis incl. 3D-sound perception, localization Binaural beats Blind signal separation Combination tone (also Tartini tone) Deutsch's Scale illusion Equivalent rectangular bandwidth (ERB) Franssen effect Glissando illusion Hypersonic effect Language processing Levitin effect Misophonia Musical tuning Noise health effects Octave illusion Pitch (music) Precedence effect Psycholinguistics Rate-distortion theory Sound localization Sound of fingernails scraping chalkboard Sound masking Speech perception Speech recognition Timbre Tritone paradox References Notes Sources E. Larsen and R.M. Aarts (2004), Audio Bandwidth extension. Application of Psychoacoustics, Signal Processing and Loudspeaker Design., J. Wiley. External links The Musical Ear—Perception of Sound —Simulation of Free-field Hearing by Head Phones GPSYCHO—An Open-source Psycho-Acoustic and Noise-Shaping Model for ISO-Based MP3 Encoders. Definition of: perceptual audio coding Java appletdemonstrating masking Temporal Masking HyperPhysics Concepts—Sound and Hearing The MP3 as Standard Object Cognitive musicology Music psychology Acoustics