This view is actually based on overall understanding or the revelation of the scripture; that God reveals his truths and communication through various means. We know of examples where God even opened the mouth of a donkey and made him talk. (Numbers 22). In the New Testament Jesus clearly promised us of the works of the Holy Spirit (John 16). Thus it is rather an implicit case from the whole Bible that we learn that God or his Spirit might talk or communicate with us indirectly, rather than a heavenly voice or direct communication.
Romans 1:20 For his invisible attributes, namely, his eternal power
and divine nature, have been clearly perceived, ever since the
creation of the world, in the things that have been made. So they are
without excuse. (ESV)
19 My brothers, if anyone among you wanders from the truth and someone brings him back, 20 let him know that whoever brings back a sinner from his wandering will save his soul from death and will cover a multitude of sins. (ESV)
2Tim 2:21 Therefore, if anyone cleanses himself from what is dishonorable, he will be a vessel for honorable use, set apart as holy, useful to the master of the house, ready for every good work. (ESV)
1Cor 3:9 For we are God's fellow workers. You are God's field, God's building.(ESV)
1Thess 5:11 Therefore encourage one another and build one another up, just as you are doing. (ESV)
If his attributes are revealed to us through nature, his voice is also revealed to us through subtle indirect things, not just through people's advice but through anything. It depends on the us as to listen to him.
General reference on God's guidance that you might use as reference:
Gen 12:1; Exod 13:21; Exod 15:13; Exod 33:13-15; Num 10:33; Deut 32:10; Deut 32:12; 2Sam 22:29; 2Chr 32:22; Neh 9:19-20; Ps 5:8; Ps 23:2-3; Ps 25:5; Ps 25:9; Ps 27:11; Ps 31:3; Ps 32:8; Ps 48:14; Ps 61:2; Ps 73:24; Ps 78:52; Ps 80:1; Ps 107:7; Ps 139:9-10; Ps 139:24; Prov 8:20; Isa 40:11; Isa 42:16; Isa 48:17; Isa 55:4; Isa 57:18; Isa 58:11; Jer 3:4; Luke 1:79; John 10:3-4; John 16:13
This question reminds me of the interview of Andrew Klavan on Jewish Voice on his book The Great Good Thing: A Secular Jew Comes to Faith in Christ where he explained how God kept calling and helping him through subtle messages and things in life. He shared an incident where as an unbeliever he was on the verge of committing suicide, but he saw a Christian baseball player on TV whose direct pro-christian messages were so annoying to him; but that night the player said "sometimes you have to run in pain", an indirect secular message which saved Andrew from committing suicide. He of course later realized that God was helping him all along.