When sound waves are emitted from a loudspeaker, they can indeed interfere with each other. However, the specific interaction between the sound waves coming from the front port and those coming directly from the cone depends on several factors, such as the relative distances, the wavelengths, and the phase relationships between the waves.
In some cases, destructive interference can occur, resulting in a reduction of the overall sound level at certain locations. However, loudspeaker design and engineering typically aim to minimize such destructive interference and optimize sound reproduction. Here are a few reasons why destructive interference may not be significant:
Frequency-dependent effects: Destructive interference is more likely to occur when the wavelengths of the sound waves are large compared to the distances involved. At higher frequencies, where the wavelengths are smaller, the effects of interference are generally less pronounced. This is because the relative differences in path lengths become less significant.
Enclosure design: Loudspeakers are typically designed with enclosures that can help control the radiation pattern of sound waves. By carefully designing the shape and geometry of the enclosure, sound waves from different parts of the speaker can be controlled and directed in a way that minimizes destructive interference.
Crossover networks: Multi-driver loudspeakers often use crossover networks to divide the audio signal into different frequency bands and direct them to specific drivers (such as woofers, midrange drivers, and tweeters). The crossover design ensures that each driver operates within its intended frequency range, minimizing interference between drivers.
Acoustic baffling: Internal structures within the loudspeaker enclosure, such as baffles and absorptive materials, can help mitigate interference effects by diffusing and absorbing sound waves. These structures help minimize the reflection and interaction of sound waves that could cause destructive interference.
While it is possible for destructive interference to occur between sound waves emitted from different sources within a loudspeaker, the design and engineering considerations mentioned above help mitigate such effects and optimize the overall sound reproduction.