How do we know the joyful sound referred to in Psalm 89?

In Psalm 89, the phrase 'the joyful sound' alludes to the gospel and the liberty it proclaims. It echoes the sound of a jubilee trumpet, which signified freedom from bondage and the restoration of inheritance. The joyful sound represents the good news of Christ's work—His grace, mercy, and forgiveness to sinners. It’s a sound highlighting the pardon granted through Christ's blood, capturing the essence of the gospel. Thus, knowing this joyful sound is essential for believers, as it shapes their identity and assures them of God’s blessings and grace, reflected in their daily walk.