'dog_bark' => 0
'children_playing' => 1
'air_conditioner' => 2
'street_music' => 3
'gun_shot' => 4
'siren' => 5
'engine_idling' => 6
'jackhammer' => 7
'drilling' => 8
'car_horn' => 9
================
'starting_index' => 0