Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2022	May 02, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Entity Registrant Name	Decibel Therapeutics, Inc.
Entity Central Index Key	0001656536
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		24,964,502
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity File Number	001-40030
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-4198709
Entity Address, Address Line One	1325 Boylston Street
Entity Address, Address Line Two	Suite 500
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02215
City Area Code	617
Local Phone Number	370-8701
Title of 12(b) Security	Common stock, par value $0.001 per share
Trading Symbol	DBTX
Security Exchange Name	NASDAQ
Document Quarterly Report	true
Document Transition Report	false