
PLAY IT BACK: ITERATIVE ATTENTION FOR AUDIO RECOGNITION
Alexandros Stergiou1,2,∗, Dima Damen3
1Vrije University of Brussels, Belgium 2Interuniversity Microelectronics Centre, Leuven, Belgium
3University of Bristol, United Kingdom
ABSTRACT
A key function of auditory cognition is the association of
characteristic sounds with their corresponding semantics
over time. Humans attempting to discriminate between fine-
grained audio categories, often replay the same discriminative
sounds to increase their prediction confidence. We propose an
end-to-end attention-based architecture that through selective
repetition attends over the most discriminative sounds across
the audio sequence. Our model initially uses the full audio
sequence and iteratively refines the temporal segments re-
played based on slot attention. At each playback, the selected
segments are replayed using a smaller hop length which rep-
resents higher resolution features within these segments. We
show that our method can consistently achieve state-of-the-
art performance across three audio-classification benchmarks:
AudioSet, VGG-Sound, and EPIC-KITCHENS-100. 1
Index Terms—Audio classification, playback, attention
1. INTRODUCTION
Audio recognition is the task of categorizing audio with dis-
crete labels that semantically represent the emitted sounds.
This includes significant challenges considering the similarity
in object sounds (e.g. boat motors and road vehicles), musi-
cal instruments (e.g. guitar, banjo, and ukulele), human (e.g.
wail and groan), or animal (e.g. yip and growl) sounds.
In everyday life, we repeat parts of songs or ask for some-
one to repeat themselves to better understand audio. This re-
lates to the development of echoic memory which is responsi-
ble for the memorization of sounds [1,2]. Therefore, repeated
listens and replays of sound stimulants [3] are an essential part
of learning and associating sound patterns.
Driven by the perception of sound through echoic mem-
ory and the recent success of Vision Transformers (ViT) [4]
at utilizing global context information, we propose an end-
to-end attention-based model that recognizes sounds through
discovering and playing back the most informative sounds
from the audio sequence, as shown in Figure 1. We use
slots [5] to attend to category-relevant sounds in the input se-
quence. These slots select the time segments to be replayed.
∗Work was done while A. Stergiou was at the University of Bristol.
1Our code is available at: tinyurl.com/playitback2023
motorcycle engine outboard motor Hercules beetle
Salient regions slowed & played-back
Fig. 1:Playback of discriminative sounds. Given an audio
sequence, the most relevant sounds are selected and played
back at reduced hop length. The generated playbacks attend
solely informative sounds at a higher temporal resolution.
Coarser features from earlier playbacks are memorized along-
side finer (i.e. higher-temporal resolution) features from later
playbacks with the use of a transformer decoder.
Our contributions are as follows: i) We propose to se-
lect and replay relevant audio features with decreased hop
lengths, slowing down relevant parts of the audio. ii) We pro-
pose an end-to-end transformer architecture for audio recog-
nition that jointly selects and attends to multiple audio re-
plays, and refines the final class predictions. iii) Our method
achieves state-of-the-art performance on AudioSet [6], VGG-
Sound [7], and EPIC-KITCHENS-100 [8].
2. RELATED WORK
Audio recognition. A popular approach for audio classifica-
tion has been the use of convolutional networks, previously
used for image-based object recognition [9,10,11] or video
classification [12] tasks, to learn features from audio spectro-
grams. The introduction of Transformer-based architectures
has further given rise to their adaptation for audio recognition
by works relying on hybrid architectures [13,14,15]. Simi-
lar attempts have also built on image-pretrained Transformer
models for attending audio spectrograms [16,17]. [18] incor-
arXiv:2210.11328v2 [cs.SD] 12 Mar 2023