Primo 4M and Primo 4P is Bach Hearing Aid's high-end family of products. Primo 4M and Primo 4 Pelivers cutting-edge features and high performance. This series incorporates both 128-band adaptive noise reduction and an adaptive feedback canceller for a complete high-end solution. The Primo line of hearing aid are custom-made hearing instruments. An impression is made of the user’s ear canal. Each Primo hearing aid is custom-molded to the shape of the user's ear canal. Primo offers In-The-Ear (ITE), In-The-Canal (ITC) and Completely-In-Canal (CIC) models. The user's level of hearing loss and preference of discreetness will determine which Primo model will fit best for the user’s needs. With the full functionalities and power of the larger Behind-The-Ear (BTE) hearing aid models, Primo adds the benefit of providing the highest quality of sound combined with the comfort of having the device custom-molded to the user's ear canal. Primo 4's adaptive noise reduction preserves perceived speech levels without causing distortion. It monitors noise levels independently in 128 individual bands. This strategy also employs advanced psychoacoustic models to eliminate audible noise and reduce the amount of perceptible artifacts introduced by the noise reduction algorithms. Based on a feedback cancellation method, Primo 4's adaptive feedback cancellation algorithm provides increased maximum stable gain unlike other feedback strategies. Additionally, it features rapid adjustment for dynamic feedback situations, immunity to tonal inputs and much more. In addition to these adaptive algorithms, Primo 4 also supports the following features: Directional processing, cross fading between audio paths for click-free memory changes, 8-band graphic equalizer, 8 generic biquad filters, optional peak clipping, flexible compression adjustments, programmable tones for memory change and low battery indicators, wideband gain, and volume control.