  State-of-the-art ASR systems have achieved promising results by modeling
local and global interactions separately. While the former can be computed
efficiently, global interactions are usually modeled via attention mechanisms,
which are expensive for long input sequences. Here, we address this by
extending HyperMixer, an efficient alternative to attention exhibiting linear
complexity, to the Conformer architecture for speech recognition, leading to
HyperConformer. In particular, multi-head HyperConformer achieves comparable or
higher recognition performance while being more efficient than Conformer in
terms of inference speed, memory, parameter count, and available training data.
HyperConformer achieves a word error rate of 2.9% on Librispeech test-clean
with less than 8M neural parameters and a peak memory during training of 5.7GB,
hence trainable with accessible hardware. Encoder speed is between 38% on
mid-length speech and 56% on long speech faster than an equivalent Conformer.
(The HyperConformer recipe is publicly available in:
https://github.com/speechbrain/speechbrain/tree/develop/recipes/LibriSpeech/ASR/transformer/)
